The Best Hydroponics Book, Volume 1

MBR

ISBN 0-9687063-0-4

4 J & S

Index

Chapter # Title

1 Hydroponics Introduction!

2 Salinity!

3 Computer Automation!

4 Fertilize Me Baby!

5 Lighten Up!

6 p-What?!

7 CO2!

8 SupercalifragilisticexpiAeroponics!

9 Helllooooooo Poly!

10 P.B.!

11 Electronic Ultrasonic Aeroponic Fogarific Hydroponics Nutrient
Delivery System!

12 Spigots!

13 Oxygen!

14 Nutrient Cycling!

15 Bio-Filters for Fish-Pee!

16 Silicon!

17 Fungus-Gnats!

18 Spider-Mites!

19 Whitflies!

20 Cloning Clinique pt. 1!

21 Intro. 2 Organic Hydroponics pt. 1!

22 Hydroponic Jalepenos!

23 Organic Plastic!

24 Hydroponic Lettuce!

25 Hydroponics Gardening on a Gradient!

26 Pearlite! Perlite! Rah! Rah! Rah!

27 Yardoponics!

28 Gravimetric Cost-Reduced Redundancy-Optimized Hydroponics!

29 Evapo-transpiration Control in Hydroponics!

30 Hydroponics Zonimetrical Gardening!

31 Hydroponics Viruses, Bacteria, and Fungi!

32 Hydroponics Plastics!

33 Back 2 Basics!

34 Back 2 Basics Part Deux!

35 Back 2 Basics Part Três!

36 Back 2 Basics Part Vier!

37 Back 2 Basics Part V!

38 Back 2 Basics Part Seks!

39 Back 2 Basics Part 7!

List of Acronyms:

Term Acronym

Controlled Environment Agriculture CEA

Electro-conductivity EC

High Pressure Sodium HPS

Metal Halide MH

Light Emitting Diode LED

National Aeronautics and Space Administration NASA

Photosynthetically Active Radiation PAR

Power of Hydrogen pH

Polypropylene PP

Electrostatic-dissipative ESD

Polystyrene PS

Polyethylene PE

High-Density HDPE

Low-Density LDPE

Photosynthetic Photon Flux Density PPFD

Transistor-Transistor-Logic TTL

Glossary of Terms:

Term Class Feature

Aeroponics Plant growth method Allows media-less culture

ex. Aeroponics is a plant culture technique whereby plants are fed by
having a nutrient solution sprayed onto their bare roots.

Bio-reactor Bio-mechanical device Turns waste into plant food

ex. A bio-reactor can turn plant and human waste into plant food.

Electro-conductivity Measurement criteria Shows nutrient
concentration

ex. The electro-conductivity of pure water is nearly zero, but it rises
as fertilizers or other ionic compounds are added into solution.

Flywheel Mechanical device Stores electricity

ex. A flywheel can be used to store electrical energy supplied by solar
arrays as kinetic energy in a magnetic mass spinning inside a conductive
case.

Hydroponics Plant growth method Maximizes oxygen supply

ex. Hydroponics is a method of growing plants in soil-less media or
directly in nutrient solution.

Photosynthetically

Active Radiation Energy form Facilitates photosynthesis

ex. Photosynthetically Active Radiation is the radiant energy required
by plants to photosynthesize.

Transpiration Plant function Moves water

ex. Transpiration is the process where plants take up water and then
give it off as a vapour, it is comparable to mammals’
perspiration.

Xerohyte(ic) Plant/Biome type Drought tolerant or dry

ex. Xerophytic plants like Cacti can thrive in arid, desert like
habitats.

Chapter #1: Hydroponics
Introduction!

Hydroponics is the water-based growth of plants, usually
directly in water or in soil-less mix, although there are many variations.
Because of the ability to have control over water and nutrient solution
management as well as increasing oxygen levels in the root zone, crop
productivity can be increased significantly when compared to regular
outdoor growing methods.

Many people immediately picture some high-tech apparatus used only by
NASA Engineers or University students when they hear the word Hydroponics,
but the truth is that Hydroponics culture methods have been successfully
used to grow ornamental and edible crops for millennia. One of the first
documented Hydroponic gardens was the famed Hanging Gardens of Babylon in
Iraq @ http://ce.eng.usf.edu/pharos/wonders/gardens.html
. Mother Nature has also been busy using Hydroponics anywhere that plants
grow in sand, gravel, etc..

Hydroponics methods are now widely employed around the world,
especially in Temperate regions where greenhouses can be operated year
round without the need for supplemental heating. Many different crops are
grown including Strawberries, Cucumbers, Lettuce, Tomatoes and Orchids.
Virtually any plant can be grown Hydroponically as long as the specific
water and nutrient consumption rates of that plant are taken into
account.

There are a myriad of different techniques used, with the Wick,
Nutrient Film Technique(NFT), Floating Raft, Drip, and Ebb & Flow
methods being the most prevalent. Aeroponics is a new twist that is
basically a method of feeding the plants by misting the roots with
nutrient solution.

The Wick method consists of having pots or a tray full of media with
plants in it above a reservoir of fertilizer solution with wicks
transferring the solution to the plants through capillary action. This is
the most basic system, but works well.

The NFT system works by having troughs or pipes which the plants are
kept in with a steady stream of nutrient solution pumped through. The
solution level is kept at a thin film to maximize the oxygen available to
the plants roots.

The Floating Raft technique consists of growing the plants on floating
Styrofoam rafts on an aerated nutrient solution. This system is best
suited to growing lettuce and other small leafy plants that don't require
much support.

An excellent link for the Floating Raft method is http://www.cals.cornell.edu/dept/flori/lettuce/index.html
that is the CEA hydroponics site at Cornell University.

The Drip method works be having the plants in pots or trays and the
solution is supplied by pipes and dripped onto the roots.

The Ebb & Flow system works by having the plants kept in a raised
tray into which the nutrient solution is pumped and then drained.

The management of the nutrient solution is of great importance when
growing plants Hydroponically. Most growers mix there nutrient solution
from commercial grade powdered mixes or from raw chemicals and top up the
solution until imbalances occur. These imbalances occur because there are
certain nutrients present in most water supplies which can build up to
toxic levels in the solution after time due to the fact that the plants
don't use them such as Sodium and Chlorine. Some facilities use
Re-circulating solutions to minimize waste fertilizer being dumped and
they are usually forced to use pure, filtered water to avoid the toxic
build-up problem.

The pH value of the solution, which is a measure of the acidity or
alkalinity, must also be monitored to keep the plants growing at optimum
levels. The pH can be adjusted by adding acids or bases as required.

There is a vast array of different growing substrates available today,
with Perlite, Vermiculite, Peat Moss, Coconut Husks(Coir), Sand, Gravel,
polyurethane blocks and Rockwool being some of the most popular. Recently,
Perlite has become the favourite of many commercial and hobby growers,
with Rockwool also being popular, but it requires pH adjustments due to
its Alkalinity. I hope this chapter has given you a good basic
introduction to Hydroponics and you should visit the list of links to
Hydroponics related sites at http://www.suite101.com/ for more
information.

Chapter #2: Salinity!

One major hurdle facing growers who wish to re-circulate their
hydroponic nutrient solution in order to reduce waste is the build-up of
toxic salts over time. This problem has also caused the destruction of
large amounts of surface soils in arid and semi-arid countries around the
world.

The most common problem salts in water supplies are; chlorides and
sulfates of calcium, magnesium, sodium, and potassium (Bray, 1990). These
salts accumulate because insufficient rain falls to purge them from the
soil. They can be removed through leaching or conversion with Gypsum
and/or Sulfur and Sulphuric acid, and evaporation control (Bray, 1990).
Reverse-osmosis water filtration units can also be used for nutrient
top-up. Alternatives include precipitation and removal with activated
charcoal.

Canadian researchers at the University of Toronto have made a
breakthrough discovery that could help to reclaim vast amounts of
farmland. They have apparently successfully transformed normal plants into
plants that will accumulate a much larger Sodium load than usual. Go to http://www.cbcnews.cbc.ca/cgi-bin/templates/view.cgi?/news/1999/08/19/farmsoil990819
for more information.

References: Brady, Nyle C.. The Nature and Properties of Soils. New
York, New York. Macmillan Publishing Company: 1990.

Chapter #3: Computer Automation!

This chapter focuses on various methods and technologies involved with
Hydroponics system automation.

The usual variables which are controlled through automation are light
and watering cycles, Electro-Conductivity (EC) which relates to nutrient
concentration in solution, pH (acidity/alkalinity which will be discussed
in detail in a future article) of the solution, and atmospheric
temperature and humidity.

The control of light and watering cycles is easily achieved through the
use of timers that can be bought at the local hardware store. Relays can
be used where switching high currents is required for lots of lights. For
automation freaks, computer systems are available from http://www.x10.com/ and http://www.honeywell.com/ which can
be used to control lights, pumps, etc..

The EC of the solution is best monitored using an electronic meter
which measures the conductivity of the solution which rises according to
concentration of ions and the units are micro-Siemens per centimeter
(uS/cm). These can be purchased from many companies like http://www.hannainst.com/ . These
meters cannot actually measure the nutrient parts per million (ppm)
because of the varying solubility to conductivity ratios of different
substances, but some are calibrated to convert from EC to ppm according to
the assumption that ~2uS/cm=1ppm. Computer automation for EC control can
be achieved using simple software to control a probe wired through an
analogue to digital converter (A/D) and into a computer or
micro-controller which can then turn on a pump to add more nutrients when
required. A/D chips can be bought for ~$2 from http://www.jameco.com/ or http://www.dalsemi.com/ or http://www.microchip.com/ .

The pH of the solution can also be monitored using electronic devices,
but it has been our experience that it is more efficient to use pH
indicating kits which contain Bromthymol Blue or other substances which
react to turn certain colours for different pH values. These kits can be
purchased in pet/aquarium/superstores. The electronic pH meters work OK,
but the glass electrodes corrode naturally as they work, and have to be
replaced. Proper media should be selected to reduce the possibility of pH
fluctuations. This is one reason why many other growers choose to use
Perlite (Pearlite) and other substances rather than Rockwool due to the
fact that Perlite is pH neutral, whereas Rockwool is alkaline in nature
and usually requires acid treatment.

Temperature and humidity are easily controlled using thermostats and
de-humidistats connected to exhaust fans.

There are very complex computer modelling software packages being
developed which will be able to predict the amounts of nutrients required
by crops in re-circulating systems according to environmental conditions,
but these programs are in their infancy, one prototype can be found at http://res.agr.ca/harrow/software/software.htm
.

Chapter #4: Fertilize Me Baby!

Plants grown Hydroponically must have all of their required
nutrients supplied in the fertilizer nutrient solution rather than
obtaining them from the soil like traditional crops in the field. This
allows for greater control of the growing environment, but can also lead
to deficiencies if all the required elements are not in the solution.

Many studies have been done by plant physiologists over the years to
determine the concentrations of nutrients that plants require and a
recognised authority in this field is Dennis R. Hoagland who developed the
"Hoagland's solution" which is a benchmark for optimal plant growth and is
used all over the world.

The essential micro- and macro-nutrients which all plants require and
their tissue concentrations for optimum growth are:

Macro-nutrients(%):

Sulfur 30

Phosphorus 60

Magnesium 80

Calcium 125

Potassium 250

Nitrogen 1000

Oxygen 30000

Carbon 40000

Hydrogen 60000

Micro-nutrients(ppm):

Molybdenum 0.001

Copper 0.10

Zinc 0.30

Manganese 1.0

Iron 2.0

Boron 2.0

Chlorine 3.0

(Taiz & Zeiger, 1991)

Certain plants such as rice also require Silicon for proper growth.

One problem with growing plants in Hydroponics nutrient solutions is
Iron deficiency that can occur due to the Iron precipitating (coming out
of solution as a solid) into insoluble Iron Hydroxide. Modern fertilizers
use chelating agents such as ethylenediaminetetraacetic acid (EDTA) which
keep the iron and other trace elements in solution. Precipitation of other
substances such as Calcium Phosphate can occur if concentrated nutrient
solutions are prepared, so solutions are best prepared separately prior to
dilution and use, usually in 2-part "A" & "B" solutions.

Most commercial Hydroponics growing operations use premixed fertilizers
to reduce the chances of nutrient deficiencies occurring caused by human
error and to reduce the labour involved in ordering and preparing nutrient
solutions from scratch. Various recipes used for lettuce, tomatoes, and
cucumbers can be found at : http://www.cals.cornell.edu/dept/flori/lettuce/stock.html

http://www.usu.edu/~cpl/nutrwht.html

http://res.agr.ca/harrow/bk2/cuke1a.htm

http://res.agr.ca/harrow/bk/tomch9.htm

http://www.ag.arizona.edu/hydroponictomatoes/nutritio.htm

http://members.tripod.com/Client_Profile/l_form.htm

http://www.biotron.slu.se/bio3375.htm

http://edis.ifas.ufl.edu/scripts/htmlgen.exe?DOCUMENT_VH030

http://www.np.edu.sg/~dept-bio/sssc/nutr.html

http://www.hbci.com/~wenonah/hydro/nitragen.htm

http://www.atlantic.net/~elifritz/hydroponics.htm

http://nfrec-sv.ifas.ufl.edu/nutrient_solution.htm

Another good source for recipes is the Journal of Plant Nutrition, esp.
Vol. #21. Issue #10 which compares 12 different solutions.

Also, check out

http://www.hydromall.com/info/eleccon.html

for values.

The units of measuring fertilizer solution concentration are Siemens
and Mhos where 2 microSiemen(uS)=2 micromho(umho)=~1 ppm(approximation).
Siemens and Mhos are units of Electrical Conductivity (EC) as described in
an earlier article and are reciprocals of resistance (Ohms) as the EC of
solutions increases linearly with nutrient concentration. Typical nutrient
concentrations are from 1000-3000 uS/cm (~500-1500 ppm) depending on size,
type of, and growth rate of the plants.

You can prepare your own calibration solution by calculating using the
equation C=Q/V where C=concentration desired, Q=quantity of solute, and
V=volume where 1g/L=1000ppm.

References: Taiz & Zeiger. Plant Physiology. Redwood City,
California. The Benjamin/Cummings Publishing Company: 1991.

Chapter #5: Lighten Up!

Plants have evolved over many eons through natural selection (except
maybe in Kansas) to use the energy available to them in Sunlight as
efficiently as possible. This part of the spectrum which plants use is
defined as Photosynthetically Active Radiation(PAR). PAR light output is
usually expressed in units of micro-moles(umol) or micro-Einsteins(uE)of
quanta per Watt(W) and measured in umol or uE per square metre per second
((umol*m-2)*s-1 ((umol/m2)/s) or (uE*m-2)*s-1 ((uE/m2)/s)) of
Photosynthetic Photon Flux Density(PPFD).

Human eyes have developed to utilize different wavelengths for vision
as seen in the (rough) graph which shows the relationship between the
daylight spectrum that reaches the Earth and the wavelengths used by
plants and humans. As you can see, plants only use certain wavelengths of
the electromagnetic spectrum, peaking in the blue and red regions, while
the human eye can best see light in the yellow area, with the "Lumen"
being used to relate the amount of light put out by bulbs that the human
eye can see.

Supplemental lighting is required in greenhouses and grow-rooms when
insufficient daylight is available. The artificial light source of choice
must have an output that will match, as closely as possible, the spectrum
plants required for photosynthesis. While the amount of Lumens put out by
bulbs can give a rough estimate of which bulb to use, PAR ratings are more
useful when choosing lights for plants and conversion factors are
available to convert from Lumens to PAR ratings for most light sources.
Metal Halide (MH) and High Pressure Sodium (HPS) lamps put out about 14
umol PAR per klux, White fluorescent give ~12 and Incandescent give ~20,
but HPS can give up to 120-140 klumens per 1000 Watts while MH give only
80-100, Fluorescent give ~70 and Incandescent give only ~20. "Gro" bulbs
put out slightly more. Compact fluorescent bulbs can put out close to
~3000 lumens @ 40 watts. Halogen bulbs can also be useful because of ease
of implementation. Greenhouses and also many university Phytotrons use
various types and combinations of bulbs.

When no daylight is available at all (i.e. indoors), some supplemental
MH and fluorescent lighting is usually used because the HPS lamps put out
a reddish spectrum which can lead to plants getting "leggy" (spindly) if
some additional blue light isn't added.

The accepted value for optimal growth of lettuce & spinach is
200-300 umol*m-2*s-1 PAR PPFD, so a 1000W HPS system putting out 140
klumens @ 14 umol*m-2*s-1/klux will give 1960 umol*m-2*s-1 which divided
by 250 for good illumination & optimal growth gives 7.8 square meters
or ~70 square feet maximum for each unit (Roughly), for a more accurate
calculation using Illumination Engineering Society guidelines for
calculations involving Room Surface Dirt Depreciation, Lamp Lumen
Depreciation, etc. please download our calculator from:

http://hydroponics.hypermart.net/light.exe

The recommended level for tomatoes and cucumbers is ~100 umol*m-2*s-1
and listings for other plants can be found in the Illumination Engineering
Handbook in most libraries (footcandles * 10.7 =lux and lux * 0.93=f.c.).

Check
out:http://www.animalnetwork.com/fish2/aqfm/1998/nov/features/1/default.aspandhttp://www.biocontrols.com/aero65.htmfor
more info..

Chapter #6: p What ?!

As alluded to earlier, the pH of hydroponic solutions is an
important factor to regulate for optimal plant growth. The term pH comes
from the French "pouvoir hydrogen", meaning the "power of hydrogen". Pure
water has a pH of 7.0 and acidic solutions have more free hydrogen atoms
and a lower pH (<7) and basic or alkaline solutions have a higher pH
(>7) and less free hydrogen atoms (Bailar, et. al., 1989).

In hydroponics, the pH value has a greater significance with respect to
nutrient availability than in regards to cellular damage which can be
inflicted by extremely acidic (pH=<4) or basic (pH=>9) nutrient
solutions. This is because molecules of nitrogen, sulfur, etc. become
insoluble at lower pH values and at higher pH’s, ions such as iron,
copper, and phosphorus can precipitate out of solution. Therefore, proper
solution pH must be maintained to ensure proper plant growth.

As mentioned in my previous article, the best way to check the solution
pH is to periodically ( 1ce a day or so) check it using a cheap pH test
kit. The more expensive meters work, but are unnecessary as rapid pH
fluctuations should not occur, and if they do, you likely have some other
problem such as supplying nitrogen as nitrate (NO3) alone, rather than
applying it in combination with ammonium (NH4) which will help to
eliminate quick rises in the pH (Taiz & Zeiger, 1991).

As the plants remove nutrients from the solution, the pH will naturally
rise slowly and become more alkaline, which must be counteracted with
acids; nitric, phosphoric and sulfuric being the most common used. In
contrast, if solution acidity is a problem (which happens rarely)
potassium or calcium hydroxide can be added, or lime added to the growing
medium will often help and is good practice to buffer pH fluctuations.

Different plant species have been experimentally shown to grow best in
different pH ranges, with acid loving plants such as Azaleas, Rhododendron
and Cranberries growing best in the pH 4-5 range. Plants such as Soybeans,
Tomatoes, Cowpeas, Cucumbers, etc. prefer to be grown in solutions with an
optimum pH of 6.0 and other plants such as Lettuce, Cabbage, Carrots, etc.
prefer a slightly higher pH of 5.5-8 (Brady, 1990). As a general rule, a
pH of 5.7-6.0 is best for most food crops.

Check outhttp://www.hydromall.com/info/eleccon.htmlfor data.

p.s. According to differential solubilities, most plant nutrient ions
are most readily available in solution from ~pH 5.5-8 depending. They can
precipitate out of solution or become bound outside of this range causing
the TDS to drop. Fertilizers are also usually acidic and will lower the pH
when added along with raising the TDS. When plants selectively deplete
ions from the solution lowering the TDS, the pH will usually rise
accordingly.

References:

Bailar, et. al.. Chemistry. Orlando, Florida. Harcourt Brace
Jovanovich, Inc.: 1989.

Brady, Nyle C.. The Nature and Properties of Soils. New York,
New York. Macmillan Publishing Company: 1990.

Taiz & Zeiger. Plant Physiology. Redwood City, California. The
Benjamin/Cummings Publishing Company: 1991.

Chapter #7: CO2!

This chapter is about carbon dioxide (CO2) fertilization. Plants
require CO2 to use in the photosynthetic cycle where it and water vapour
chemically combine producing carbohydrates (sugars) for energy, and
releasing Oxygen and excess water vapour.

CO2 becomes a limiting factor for growth when sufficient light, water
and fertilizer levels are available as the CO2 is depleted by the plants
and must be replaced by venting or supplementation. The atmospheric
concentration of CO2 is ~0.035% (~350 parts per million (ppm)), and plants
have been shown to have up to a 200% increase in growth at 700 ppm (Taiz
& Zeiger, 1991). The accepted value for maximum growth of most crop
plants is 1500 ppm CO2. CO2 levels should not be increased in areas where
humans and/or other animals could be exposed, without all proper safety
precautions being implemented.

CO2 can be supplied by various means, including injection from
compressed tanks of liquid gas, production via combustion, fermentation,
chemical reaction and catalytic combination. Tanks of compressed gas and
combustion are the two most common methods for CO2 fertilization, with
combustion being mainly used in outdoor greenhouses in cooler climates
where excess heat can be used. The fermentation method using brewer's
yeast can be applied to small grow-rooms, but is messy and smelly, but
cheap and effective.

The control of the levels of CO2 available for assimilation in the
growing area can be a problem. The amount of fuel required to burn to
achieve a desired CO2 level is predictable using molecular weight
calculations, but most commercial production units are calibrated and come
with timing sheets for the production rates. When using fermentation, it
is nearly impossible to predict the exact amount that will be produced and
CO2 monitors are recommended, but are currently quite expensive. It is
easiest to use compressed tanks of the gas that can be used with
flow-meters or gages that are calibrated accordingly, usually in cubic
feet per hour (CFH) which can give you a rough estimate of the levels.
Using calibrated monitors are the most effective means to determine the
CO2 levels.

There is currently anecdotal speculation that addition of Lecithin
(Soy?) to the root zone can facilitate CO2 uptake by the roots and studies
are ongoing.

References: Taiz & Zeiger. Plant Physiology. Redwood City,
California. The Benjamin/Cummings Publishing Company: 1991.

Chapter #8:
SupercalifragilisticexpiAeroponics!

This chapter will give you a description of how to build your own cheap
and very effective aeroponic "cloning" chamber to use for quick rooting of
cuttings. We came up with this design a few years ago and it is incredibly
simple and efficient and can be completed with a few parts from your local
hardware/pet/Borg store. We will not add a picture (because we won't have
our digital camera until Christmas), so you will have to use your
imagination.

The parts you will need are:

-Rubbermaid™ or other suitable plastic or plastic-lined wood box or
aquarium

-water pump (~>200GPH), preferably magnet driven & fish-safe
(those are usually corrosion proof and made to run continuously)

-some plastic sheet (preferably white)

-Exacto™ knife

-misting, nebulizing, vaporizing (vapourizing), or atomizing head(s)
from the lawn-sprinkler/garden department of the store (try to get them in
full circle 360 degree coverage) you could also order on-line @:

http://www.truefog.com/catalog.html

http://www.kesmist.com/homepage.htm

http://www.raindrip.com/

or you can use an ultrasonic fogger mister when they are readily
available

-some poly pipe & fittings

Firstly take the lid of the container & cut some dime-sized holes
in it, approximately 3-6 inches apart. Then attach your misting nozzle to
the pump on a 5-10 inch riser (piece of poly pipe) and place it in the
bottom of the container and add enough water to cover the pump + a few
inches extra so it doesn't run dry and test the nozzle to see what kind of
spray pattern you get. There is a myriad of misting nozzles available
around the world, so the toughest part of this endeavour will be to fit
the nozzle(s) to your pump so you get a good mist going in the container.
You may have to use a couple of heads & couplings & T's &
nipples, but everything will be available in the plumbing section of the
store. Today I went to a local hardware store (which shall remain
nameless) and purchased a head for 98 cents and it worked well enough when
attached to my 250 GPH pump to fill my box(10 gallon) with mist, I was
lucky.

When you get the pump & misting head(s) set up, you are done. Add
water and maybe 1/5th of a multivitamin (dissolve the vitamin in a jar of
water first & strain it into the box so you won't clog the mister head
with chunks), put the lid on with the piece of white plastic on top which
now has slits cut in it to poke the cuttings in through the holes, insert
your cuttings, put the pump on a timer to be on whenever light is supplied
or in intervals & you're off. Your cuttings should root in 1-3 weeks,
depending on the species. This technique won't work for all plants, but
you can test a few from around the house & garden, & some will
love it.

Chapter #9: Helllooooooo Poly!

Polystyrene (PS), High-Density Polyethylene (HDPE), Low-Density
Polyethylene (LDPE), PolyPropylene (PP), Polyethylene Terephthalate (PET),
Mylar, Nylon (PA), etc., etc.. These are a few of the labels you will find
around the house on polymer food containers. When it comes to building a
hydroponics system using polymer containers, you should use some of these
same products. Rubbermaid™ for example have assured us that their products
are safe to use for hydroponics systems. If you are building a large tray
system to be lined with poly. sheeting, you should not use something like
mildew resistant construction vapour-barrier as it may be phytotoxic
(harmful to plants) due to being impregnated with pesticides. Instead, you
should contact local plastic wholesalers or farm supply companies and tell
them what you want. You can also check out AT Plastics (who manufacture
agricultural food and hydroponics-safe polymers) at http://www.atplastics.com/ or other
plastics manufacturers and find a local distributor in your area.

There have been a few studies done lately which warn of plasticizers
that can be released from certain poly. products into foods, such as DEHA
in plastic wraps. One link for information concerning this is http://www.plasticsinfo.org/food/index.html
and certain scientists have stated that soft plastics, like the Poly-Vinyl
Chloride (PVC) should be avoided as they may release additives into the
surroundings.

There have been rumours that recycled plastics may contain high levels
of Lead &/or other toxins.

It has also been stated that "...components that come in contact with
the nutrient solution, as many as possible should be made of plastic
because metal can release potentially toxic levels of certain
micro-nutrients such as zinc and copper in the solution. Because of the
widespread use of plastics, take care to select materials that are not
phyto-toxicity. As a general recommendation, PVC and low- and high-density
polyethylene or polypropylene are acceptable, but plasticized PVC used in
the manufacture of flexible hose, or butyl rubber sheet lining, used for
waterproofing reservoirs, should not be used in NFT as they may be
phyto-toxic. Plastics are more likely to cause phyto-toxicity when they
are new. Plastic surfaces quickly lose their potential phyto-toxicity when
exposed to nutrient solution. Therefore, before planting a crop, flush out
the new hydroponic installation entirely for 1 day with a dilute nutrient
solution that is discarded." by Dr. A. P. Papadopoulos "Growing greenhouse
tomatoes in soil and in soilless media" http://res.agr.ca/harrow/bk2/cuke-toc.htm

A couple of other interesting links can be found at http://www.plasticsinfo.org/food/packaging.html
and http://www.cfia-acia.agr.ca/reference/q1-c.html#C
.

Chapter #10: P.B.!

The Perlite Bed Theory:

Perlite (a.k.a. Pearlite) Beds and their variations have to be some of
the most versatile and simplistic yet productive hydroponics systems ever
conceived. Perlite Beds can be adapted to grow plants in many
configurations including ebb-&-flo, NFT, flood-&-drain,
dripper-matrix, soaker-hose, pipe-action, etc..

Complete Perlite Bed units can be easily designed and built to fit any
space. A large poly. tray or poly. lined wooden tray arrangement with a
thru-hull fitting to a poly. or other reservoir beneath forms the basis
for each unit's functionality. The nutrient solution is pumped up to the
plants on top and flows back into the reservoir where it is controlled
& monitored.

For larger spaces, many units can be used in unison. Each unit then
serves as a modulus creating a modular expansion capability.

Perlite used alone or in combination along with other amendments such
as Vermiculite, Rockwool, Dolomitic Limestone, Peat Moss, etc. is the
medium used to form the substrate to support the plants roots.
Combinations can be mixed to allow creation of "Zones" suitable for
optimized plant growth. Perlite is cheap and easily obtained at any
farm-supply or gardening nursery store for ~$10-20/110L. The media can
also be bagged.

Fish-pumps and other types can be used. Magnetic-driven seem to be the
most efficient and trustworthy available.

The beds can be built on top of tables, sawhorses, or other support
apparatus. Minimal pH adjustment should be required with a Perlite Bed and
evapo-transpiration rates can be controlled using modified substrate
recipes and/or addition of landscape fabric or poly. sheeting or other
mulches to the medium's surface.

The bed(s) should be rinsed regularly with clean water to avoid
nutrient level fluctuations.

Chapter #11: Electronic Ultrasonic Aeroponic Fogarific
Nutrient Delivery

There is a revolutionary new product available on the market
that uses electronic vibrators to transform ordinary liquid water into
sub-micro evaporative fog mist droplets that can be used to feed and
humidify plants.

These units consist of electronic transducers that are pieces of
crystals (piezo) that vibrate according to the degree of electrical
current supplied and can be driven to such a rate that they emit
ultrasonic "beams". If they are squeezed or vibrated, they can also
release electrical current.

The micronic size of the atomized droplets allows for deep penetration
of growing chambers and optimal availability to the roots. The "fog"
created is equivalent to the white, puffy clouds floating in the sky. The
endothermic evaporative reaction producing the fog can cause the
temperature to drop, but subsequent exothermic condensation will make it
rise so the temperature must be monitored and a heater may be necessary.

Nutrients and amendments can be added to the solution as required for
delivery to the plants’ roots. Possibilities include using the units for
root or foliar treatment combinations.

Pulsing timed oscillating excitation is recommended to extend the
unit's useful life as prolonged vibration may cause degredation.

There are many sources for purchasing the technology, we will be
posting the most economically efficient manufacturers soon in the list of
Hydroponics links.

Chapter #12: Spigots!

Spigots can be very useful when designing a Hydroponics or
Aeroponics system as they allow for ease of nutrient solution monitoring
and cyclic renewal.

On the other hand, they can be a cause for concern when they leak. Care
should be taken when shopping for suitable spigots to allow for quality
assurance. Nothing can be more annoying than a leaky spigot.

Some people frown upon spigot-usage and prefer to practice spigot
elimination in the quest for dryness and leak-proofedness. Spigot
avoidance can be achieved through the use of a siphon-hose, pumps,
dumping, overflow utilization, etc.. However, certain cases require spigot
usage and we recommend you rely upon heavy-duty spigots bought from
hardware, plastic, wine, or industrial supply stores.

Both metal and polymer spigots are available, with stainless-steel and
non-recycled food-safe plastics being the most desirable construction
materials to allow for preventative solution contamination elimination.

Teflon©™® tape can come in very handy when trying to prevent leakage
occurrence, as can food-safe silicone products.

Plastic filters can be used when the spigot is to be placed in a tray
of loose media to prevent losses.

Spigots can be attained that have different modes of operation and
features. Some have a pressure-operated lever system to open, while others
have a mechanized valve that must be opened and closed by turning the knob
on the shaft. Yet others have push-button opening.

An interesting couple of links are located @:

http://www.securefuture.com/water2.html

http://www.polyflow.com.au/

Chapter #13: Oxygen!

One of the main benefits of growing plants using hydroponic and
aeroponic techniques is the maximization of oxygen in the root zone. This
abundance of rhizobial (root zone) oxygen allows for optimized root cell
respiration and maximized plant growth.

Conversely, in compacted soils or stagnant pooled nutrient solutions,
oxygen levels can be depleted to a point where cellular damage occurs in
the roots which subsequently leads to shoot growth retardation. This
depletion is caused both by the plants themselves, as well as naturally
occurring bacteria using the available oxygen faster than it can be
replenished through diffusion from the atmosphere above the soil or
substrate surface.

Low-oxygen (anaerobic) soils also allow for the growth of detrimental
bacteria which can deplete mineral nutrients such as nitrogen an sulfur,
which can ultimately lead to deficiencies and further extend crop losses.

Oxygen concentration maximization is the basis for the Nutrient Film
Technique (NFT) which uses a thin film of nutrient solution to feed the
plants and the nutrient film must be thin enough to allow for easy
oxygenation. The use of perlite (pearlite) and other substrates also allow
for increased oxygenation, but this gain in production can many times be
counteracted by practices such as wrapping blocks of media in plastic
liner, or placing plastic "mulch" over the substrate in order to reduce
evapo- transpiration. Oxygen levels can be increased in the nutrient
solution be using aeration devices like "air-stones" and pumps commonly
used in fish tanks.

Water and oxygen management is a discrete science with a balance being
achievable between crop production and water usage. Where water
consumption is not an issue, oxygenation should be increased through the
use of porous, aerating substrates. When evapo-transpiration reduction is
necessary, plastic mulch may be used more efficiently by cutting holes in
the material around plant stems to allow oxygen to feed the roots, and
transpiration-reducing wax emulsions may also be applied to the plants'
leaves and stems in moderation.

It has been scientifically proven that oxygen reduction in the shoot
zone can actually increase dry mass production, but due to associated root
zone depletion in normal practice, this is not a viable practice.

Chapter #14: Nutrient Cycling!

Some "people" practice "open-ended" cycling routine agendas
while others are constantly striving to improve their "closed" or "batch"
culture schemes.

In a perfect world a closed system could function indefinitely. You
would apply nutrients, light, CO2, & water to the system and get
plants out without any waste being produced. In reality, the system will
likely develop an imbalance and require that corrective measures be
applied. Where water conservation and pollution reduction are necessary
&/or possible, & where secondary ion depletion can be imposed on
nutrient effluent, consumption can be facilitated in an environmentally
symbiotic fashion.

Depending on circumstances allowances, nutrient solutions may be
continuously utilized by re-circulating the same batch indefinitely on
crop plants until refreshing is necessary when the old batch is optimally
"filtered" through ornamental or other crops to minimize secondary
environmental impact, or fresh mixtures of the solution are applied to the
plants during subsequent fertilizer application with any effluent being
used as described above.

Reverse osmosis filters and other types of water purification systems
allow for emergency or routine water management control. This control can
vastly elongate nutrient replenishment deferral times and reduce water
requirements.

Tissue and fertilizer solution sampling are commonly used to perfect
nutrient application recipës.

Certain regimes have been applied successfully where nutrients are
applied in a one-way-street fashion where all moisture applied is to be
processed by the plants without allowing for re-circulaition or expulsion,
but these routines can be difficult to manage as evapo-transpiration rates
are often difficult to foresee or predict in unison with nutrient level
maintenance. Nutrient deficiencies &/or toxicity symptoms are risks
which can be managed.

Chapter #15: Bio-Filters for
Fish-Pee!

Fishes excrete a higher concentration in parts-per-million (ppm
(mg/L H2O)) of waste in the form of the Ammonium (NH4+) ion in solution in
equilibrium with water than mammals because of the fact that their
hypertonic tissues can readily receive water when required by diffusion
(osmosis) from the surrounding liquid body.

In ponds, aquaria, and other biospheres which can loosely be considered
isolated "batch" or "closed" culture systems, this can result in
difficulties arising because ammonia is toxic to fish in high enough
concentrations and must therefore be removed from the solution
accordingly.

Mammals and other animals, with their limited water store &
resources, utilize chemical reactions in their bodies which convert
ammonia to less toxic urea which can be loaded to higher levels.

Activated carbon filters have been used for many generations when
unwanted ion reduction has been required. Recently other types of filters
such as "Reverse Osmosis" *("R.O.") and others have been employed.

Mother Nature has developed a system over many millennia of performing
mineral cycling which allows for re-use of ions through chemical
manipulation. The "Nitrogen Cycle" involves nitrogen being cyclically
exchanged between animals, plants, water, the soil, and the atmosphere.

Plants can readily absorb and use Nitrogen in the form of Ammonium or
Nitrate ions, and they can convert Urea into Ammonium for use to build
proteins, etc..

In soil and regions where moisture levels allow, the process of
breaking down toxic compounds like ammonia is achieved through oxidation
by bacteria into usable substances. This process is known as
"Nitrification" and is performed by the chemoautotrophic bacterium
Nitrosomonas which breaks down Ammonia (NH3) to Nitrite (NO2-) (which is
highly toxic to plants) and Nitrobacter which transforms Nitrite to
Nitrate (NO3-) which plants can use.

"Bio-filters" are apparatuses which attempt to mimic the outdoors by
creating a haven for reproduction of nitrifying bacteria. They usually
consist of a supporting form, such as a large Rubbermade® or other
container with gravel or sand or porous poly. or other material(s) inside
in mesh bags, over which the system solution is pumped, allowing for
maximum air penetration and moisture distribution. When used in
conjunction with plants, toxin and nutrient levels can be reduced and
managed as desired.

Chapter #16: Silicon!

Silicon has a plethora of uses in the known Universe including
everything from being used in flexible, heat-resistant adhesives and
sealants to forming the substrate for today’s "high-speed" computer
processors.

Certain plant species such as rice also require silicon for proper
growth, maturation, and reproduction.

There has been recent speculation and apparent experimental
justification resulting in some "authorities" concluding that silicon is
also a beneficial and in many cases essential element for optimal crop,
ornamental and other plants' physiological metabolistic cycles.

In the natural environment Silicon is present abundantly in many
classifications of soils such as Silicate minerals including the
tetrahedral ionic crystalline sheets of clays including Vermiculite,
Kaolonite, Talc, etc.. The Silicon stored in these substances is released
upon weatherisation or breakdown of the compounds and made available for
plants in the vicinity.

Organisms classified as "Diatoms" which are microscopic life-forms also
accumulate Silicon in their cellular wall structures. These beasts
manifest their existence in many aquatic environments around the world
causing the accumulation of Silicon in large quantities when they die and
build up on the water bodies' floors. "Diatomacious Earth" is sold in many
regions and consists of the mined lifeless skeletons of these diatoms
which serves to act as an insecticide because of the penetrating nature of
the minuscule particles which can block insects' air passages, resulting
in death.

In Hydroponic cultures, Silicon may be depleted when not supplied by
external means and certain scientists have performed experiments which
show that certain plants grow more vigorously when Silicon is supplied in
supplemental form such as Potassium Silicate. Diatomaceous Earth and
Vermiculite may also be used as organic natural sources of the
mineral.

Chapter #17: Fungus Gnats!

Fungus Gnats (pronounced "Phungus Nats") (Mycetophila spp.) are
disgusting, destructive insects which feed upon wet plant matter and
fungal material causing huge amounts of damage to hydroponic and
conventional crop plants world-wide on a daily basis.

These "bugs" are recognizable by their "fruit-fly"-like appearance:
i.e. they are very small black flies which buzz and flitter around the
soil/substrate/food source surface in a very annoying fashion, appearing
harmless to the naked eye.

They proliferate in moist areas where food is plentiful, such as
hydroponics gardens which have an abundance of plant material and fungi
available for them to munch on.

I have experienced infestations when growing hydroponic garlic plants.
The gnats initially appear to feed on dead plant matter and microscopic
fungi, but subsequent actual living plant damage is evident, perhaps when
they run out of fungal material and dead plant matter to ingest.

Remedies include accepting the little monsters as co-habitant existents
(this is the method preferred by vegan wussies) or decimation by
biological or chemical means. Organic Pyrethrum insecticides have been
used with great success, as have been Nematodal & Spider-mital
beneficial predatorily destruction techniques.

I will be adding a labelled diagram when I get my "new" computer in a
couple of weeks as my old 486 is getting tired, listless, and
cumbersome.

Chapter #18: Spider-Mites!

Spider-Mites (Tetranychus spp.) are parasitic pests which are
arachnids and members of the Order Acarina. They occur naturally in nature
throughout North America and in other regions around the world.

In cold winters, most will die off, but some eggs will survive and
hatch in the Spring to renew the outdoor colonies. Others will be lucky
enough to migrate into houses, barns, greenhouses and other buildings to
continue growing and breeding.

Outdoors, Spider-Mites are not usually associated with large amounts of
crop damage because of natural predation which controls the population.
Indoors without the presence of predators, where they are able to get
access to virtually unlimited food sources such as in greenhouses full of
tomatoes, beans, or other plants, they can breed and form populations
which can virtually obliterate thousands of dollars worth of plants. They
do this by feeding on the plants using their sharp, piercing mouth parts
to get access to the nutrient-rich "sap" inside leaves and stems. The
damage they inflict weakens the plants to the point where they become
susceptible to diseases such as viruses and bacteria.

Spider-Mites are very small, but can be recognized with the naked eye
as tiny white-gray dots on the underside of leaves which appear in the
presence of silky webs which harbour hundreds of eggs. Under
magnification, they look like tiny, little spiders. "Two-Spotted"
Spider-Mites (Tetranychus urticae) are very common and more hardy than
some other varieties making them worthy adversaries. They can be
differentiated from other species by the obvious black spots present on
them.

Control of Spider-Mites can be arranged though the use of "organic"
concoctions made up of Tobasco©® sauce, alcohol, tobacco, soaps, garlic,
etc., but we have found that it is more practical and efficient to
decimate the mite population using organic Pyrethrum(in/oid) sprays or
insecticidal soaps as this allows for quick plant regeneration without the
possibility of toxic shock occurring due to the build-up of control agents
in the plants' tissues and surrounding soil. Another option is to import
stealth assassin squads of predators including P. persimilis, A. fallacis,
Feltiella, and Neoseilus californicus, but again, this option is not as
fast-acting as the Pyrethrum spray. Pyrethrum sprays are supposed to be
quite safe and non-toxic to humans, and he are reported to degrade
quickly, but can also be rinsed off if desired.

Chapter #19: Whiteflies!

The greenhouse whitefly (Trialeurodes vaporiorum, Family
Aleyrodidae) is a cute, fuzzy little insect which must be destroyed to
prevent infestation and crop destruction!

These insects, like other greenhouse and indoor pests, exist naturally
outdoors and migrate inside in colder climates to survive.

The yellowish eggs hatch into white Nymphs which attach themselves to
the underside of plants' leaves with a wax-like coating. These Nymphs are
non- feeding and resemble scales.

The adults spend almost all of their time feeding on plants' juices and
hanging out underneath the leaves, making them difficult to notice and
expel. A quick shaking of plants will cause the adults to scatter and
become visible. While they resemble nice little white moths when
magnified, they are very injurious to plants.

These creatures can be controlled as other insects, using organic
pesticides or home-made concoctions of household agents, or good-old
squashing techniques can be employed with great success.

Biological control agents such as the Whitefly Parasite (Encarsia
formosa) and the Whitefly Predator (Delphastus pusillus) can be very
effective when used appropriately in pertinent circumstances. Encarsia
formosa is a tiny parasitic wasp which incubates inside the Whitefly
larvae and emerges to ingest the host. The adults also kill Whiteflies for
food. Delphastus pusillus is a little beetle which feed on Whitefly eggs,
thus interrupting the reproductive cycle and causing population depletion.

It is our opinion that organic insecticides are usually your best bet
when time is a concern, which it is in most cases when bugs are in the
midst of killing your plants

Chapter #20: Cloning Clinique
pt.1!

This week's article will be a minimalist exploration of various
techniques used for "cloning" or propagating "baby" cuttings obtained from
a "mother" plant through vegetative reproduction.

The use of an aeroponics unit, such as one described in one of our
previous articles, can make the cloning of many plants a snap or breeze,
as it were, but many people prefer to use more basic methods, which can be
just as effective and productive when perfected.

Many people are familiar with taking cuttings of such plants as ivy,
and placing them in a cup or glass or mug or vase of water until they form
roots at which time they can be transplanted to pots for growth. This
practice is the basis for the mass cutting production routines practised
in nurseries world-wide, except for various modifications according to
circumstances.

Cuttings taken from herbaceous plants can be successfully rooted in
water, moist potting soil, vermiculite, stone-wool, perlite, sand,
polyurethane foam, and various other substances and combinations.

It is best to take cuttings of stems inter-nodally (between leaf
junctions) and to include at least one de-leafed node to be inserted into
the rhizome (beneath the surface). Large leaves should be removed if
possible, leaving smaller leaves to provide preliminary photosynthetic
nourishment. Large leaves can kill cuttings when they transpire
excessively and dehydrate the plant to be.

Some people insist that using a sharp knife or razor to add cuts to the
part of the cutting to be inserted in the soil can speed root formation,
and this could be tried to see if it effective for you.

Another technique which has proven to be effective for some plants is
to place the freshly taken cuttings into a sealed plastic bag which is
then put into a cool fridge over night, allowing the plants to rest and
form a callus layer at the cut surface to aid in stress reduction and root
propagation.

Cuttings should always be kept in subdued lighting for at least 24
hours, after-which they can be put under artificial lighting or in a
well-lit area.

Many people use clear glass or poly. humidity domes, aquaria, or other
apparatuses to seal moisture into the cuttings' environmental atmosphere.
Others prefer to mist them with water regularly and still others use
anti-transpirants (such as wax) to seal in moisture so the cuttings don't
dry out.

Exotic rooting hormones such as gels and sprays laced with vitamins and
other mystical, magical secret ingredients are usually unnecessary and
good old rooting powder will suffice, but to each their own. Fungicides
may be required in unkempt, dingy surroundings, but cleanliness can
usually prevent fungal infestations.

Chapter #21: Intro. 2 Organic Hydroponics
pt.1!

People who have some sort of problem associating hydroponics
with organics should stop reading this right now and go put their heads
back in the sand. The word hydroponics can be loosely interpreted from
Latin to mean "working-water" (not "non-organic" as some people seem to
think), and since water is allowed for organic growers, hydroponic growers
can of course adapt their systems to be fully, or semi-organic.

I don't plan to rant much further, but I have run into many organic
exclusionist idealist fervour-spewing radicals who refuse to categorise
any hydroponics methods as possibly being organic off hand, without any
consideration.

Now on to the more enjoyable technical aspects of organic hydroponics.

Organic substances are defined as those substances obtained directly
from Mother Earth without chemical alteration or processing, and including
those produced by plants or animals.

A completely organic hydroponics system must use only organic materials
for the substrate or media in which the plants are intended to grow, and
must utilise only organic fertilizers to supply the necessary nutrients
for the plants to grow and flourish.

The growing media can be soil (steam or heat sterilized preferably to
prevent disease or fungal infestation), vermiculite, perlite (pearlite),
peat, coco-husk (coir), straw, or other organic material(s). I’m not sure
whether stone-wool is classified as organic by the organic classifiers,
but seeing as it is just physically treated (heated and spun) rock from
the Earth, I think it should be, although I don’t use or praise it anyway,
but some people have been convinced to like it (fanatically in some
cases).

Organic fertilizers come from a vast array of sources including bat
guano; sea-bird dung; sea-weed ("strip-mined" or "clear0cut" from the
oceans); fish entrails and bones; cow, pig, sheep, chicken manure, bones,
blood, and urine; and a myriad of other places.

The main problems with using organic fertilizers are nutrient
completeness and control issues as well as contamination problems.
Nutrient variations between batches and sources of organic nutrients make
fetilizer cycling much more difficult than with conventional "chemical"
solutions, causing increased runoff into the environment in some cases
where ion imbalances occur. Fertilizers such as manure are also sources
for possible outbreaks of E. coli bacteria when crops are not processed
properly.

When using organic nutrient solutions in hydroponics it is best to
discard waste effluent by using it to fertilize ornamental or outdoor
crops to minimize environmental damage.

Chapter #22: Hydroponic Jalepenos!

One of the easiest and most delectable crops I ever grew was a
small batch of hydroponic Jalepeno peppers grown indoors under artificial
lighting.

I set up a small grow-room ~4' x 4' and covered the walls with clean,
reflective white plastic. I erected a 3' x 3 & 1/2' ebb & flow
tray on top of a piece of plywood supported by empty 5 gallon pails, with
a 15 gallon reservoir underneath to hold the nutrient solution. Inside the
reservoir was placed a small aquarium water pump with hose to feed the
grow-tray through a thru-hull fitting which was purchased from the boating
supply section of a local hardware store.

The lighting system I used was one 400 Watt Metal Halide standard bulb
in a vertical (base-up) reflector fixture with remote mounted ballast. I
didn't bother to measure the light levels throughout the room as I
presumed I would have enough light, and could always add some fluorescents
if need be.

The substrate chosen in which to anchor the plants roots was pure
medium-grain sized horticultural-grade Vermiculite because peppers require
and flourish in moist areas.

The media was flushed with 1/2 strength fertilizer solution to "charge"
it with nutrients as it had none to begin with and would have depleted the
first batch in the cycle if this was not done.

Pepper sprouts which were incubated under fluorescent lights for a week
were transferred to the hydroponics tray and left to grow under 16 hour
light "days" and the tray was flooded once a day with solution initially
and twice after 3 weeks when the plants were larger.

The pH of the solution was checked once a week using an aquarium test
kit and it did not require adjustment due to the Vermiculite's natural
neutral state combined with the slight acidity of the fertilizer which
kept the system's level at the optimal value of pH ~6.

The fertilizer used was a commercial-grade powder type and it was mixed
according to the directions, using ½ strength for the first week and
regular full strength after that. The EC was not checked and the system
was flushed with clean water every 3 weeks and replenished with fresh
nutrients.

Due to the cleanliness of the room, no problems with fungi or pests
such as whiteflies or spider-mites occurred and a huge batch of plump,
succulent peppers was harvested with 8 weeks.

Chapter #23: Organic Plastics!

Most all modern plastics can be classified by definition as
being "organic" because they are made of compounds containing Carbon
atoms.

There is now a new breed of plastics known as Polylactide Polymers
(PLA) being developed by Cargill Dow Polymers LCC®©™. These futuristic
plastics will have a myriad of broad-reaching uses including everything
from making clothes to being used as hydroponics media.

Although many long-lasting, clean plastics are available already, as
outlined in our previous article "Helllloooo Poly.!", these new plastics
are heralded to be increasingly environmentally friendly due to the fact
that they are readily recyclable and can actually be composted if desired.
In contrast, many plastics in use today are designed to be so
indestructible that they remain intact while buried in landfills and can
take hundreds, if not thousands of years to fully decompose if they are
not recycled.

The new PLA plastics are made using carbohydrate sugars extracted from
crop plants such as corn, and they are also hoping to be able to be make
them from recycled plant material and organic waste products in the
future.

These plastics will be especially useful in agricultural circles for
use in many areas such as potting mixes, seed trays, and hydroponics media
to name a few.

Currently polyurethane and other plastics are used to make durable
rooting substrates which can be steam-sterilized and used almost
indefinitely until they are so packed with roots that they must be thrown
away or recycled if possible. The new plastics will be able to be
composted or used as mulch or soil amendments outdoors directly, saving
the environment and money.

A couple of good links are: http://www.dow.com/ http://www.cdpoly.com/

Chapter #24: Hydroponic Lettuce!

Sometime in the last millennium, at about this frosty time of
year, I set up a hydroponics unit for a "friend" in their basement to grow
some lettuce, and in this week's article I'll describe how I did it.

First, I hanged an old light fixture which contained four four foot
forty Watt cool white fluorescent tubes. I used chains attached to sturdy
hooks screwed into the ceiling beams, or floor joists above, depending on
how you look at them.

I then taped durable, easy to clean reflective white plastic in a
drape-like fashion around the perimeter of the fixture to focus all of the
available light inwards towards where the plants would soon be situated.

Next, I placed an old square three foot by four foot growing tray on
top of some old recycled five gallon wine juice pails.

I used an old twelve volt utility pump placed inside a large plastic
reservoir to supply the nutrient solution to the tray above. The pump was
powered by a power supply and it had a piece of polyethylene pipe attached
from it to the tray through a thru-hull fitting (with plastic mesh placed
over the end for filtration of chunks of substrate) to allow for flooding
and draining of the tray.

The tray was then filled with approximately four inches of perlite and
vermiculite in a ten perlite to one vermiculite ratio by volume.

I then seeded the tray by using my fingers as little "hoes" to make
furrows and then I dropped the seeds in and covered them with a thin layer
of the substrate mix. Then I watered them & covered them with waxed
paper until they sprouted.

The lights were left on a 16 hour light cycle.

I used my usual method of checking the pH rarely and replenishing the
nutrient solution according to the manufacturer's instructions bi-weekly
and using the old solution on the lawn & garden outside.

After 6 weeks of anticipation, excellent petite lettuce heads were
ready to be picked and were quite delicious.

Chapter #25: Hydroponic Gardening on a
Gradient!

When it comes to designing larger indoor or outdoor hydroponics
gardens where relatively small water reserves are preferred or required
for monitoring purposes or to reduce mass, one option is to use drip
emitters to directly target plants being grown in trays on a gradient.

Comparatively small amounts of fertilizer solution can be used in this
manner to supply very large quantities of plants. Large plastic trays, or
wooden trays lined with plastic can be laid out and adjusted to a level so
as to drain the solution back towards the nutrient container with or
without the aid of tubes and hoses.

The nutrient supply chain is usually comprised of a water pump which
expels the fertilizer solution into a series of pipes and fittings which
are directed towards the bases of the stems of the plants where they
gently deliver their load of nutritious fertilizer ions to the plants.
Professional drip emitters, osmotically permeable membranous tubes, and
soaker-hoses are available for reasonable prices at most hardware stores,
but a system of improvised drippers made from thin poly. tubing or pipes
with small holes drilled in them can easily be fashioned accordingly using
a little ingenuity.

Most any substrate can be used to harbour and support the plants' roots
in the trays, and I highly recommend perlite and/or vermiculite due to
their characteristic chemical neutrality and excellent moisture and air
holding capabilities as well as their economical cost effectiveness and
the fact that they are readily available in most areas of the world.

When using this technique to grow plants, it is good practice to
regularly flush the media with fresh, clean water to clear out any excess
fertilizer salts which could build up to toxic levels if left unchecked.

This method conserves water well and is generally easy to run and
maintain.

Chapter #26: Perlite Pearlite Rah! Rah!
Rah!

Perlite (or Pearlite) has been heralded for many years as being
an excellent constituent of soil-less mixes and has more recently been
appreciated for its astonishing performance as a hydroponics medium.

Perlite is a naturally occurring silicous volcanic rock that appears
around the world in its raw ore state as being gray-black, but when it is
quickly heated above 870 degrees Centigrade, it puffs up like popcorn and
appears white.

The puffing expansion process causes the creation of a huge internal
surface area of intertwining glass shards that allow for the respectively
large water and air holding capabilities of the substrate. The increased
volume to mass ratio also makes perlite very lightweight and easy to use.
The light weight can cause difficulties in stabilizing larger plants, but
this is usually overcome simply by using strings or netting attached to
structural supports.

This "organic" glass media has excellent water and air holding
characteristics, along with being physically durable and stable, and
chemically inert and neutral as well.

Many people prefer the air to water holding capabilities of perlite
over other substances because the balanced air to water ratio present in
perlite can reduce the chances of over or under watering due to the fact
that it provides both excellent drainage and capillary action when water
is applied.

Perlite is also very clean and sterile when purchased because of the
physical processing it endures which can reduce the possibility of fungal
or bacterial infestation occurring.

Try doing a search for "Perlite" in one of your favourite search
engines for more information.

Chapter #27: Yardoponics!

A certain "friend" of mine asked me to consult on their Spring
project this year which is to be the building of a medium sized
hydroponics unit in their back-yard when the cold breaks. This article
will discuss our plan of action.

Firstly, seeing as the person’s yard is fenced and facing to the west,
and we are in the northern hemisphere, I plan to build the unit adjacent
to the north wall for maximal Sun exposure.

The electrical line will be controlled on a line using a GFCI breaker
circuit to prevent accidents from happening.

The substrate of choice for our hydroponics unit will be Perlite with a
little Peat, Dolomitic Limestone, and Vermiculite mixed in for balance.

We will be using a commercial grade multi-purpose hydroponics nutrient
fertilizer formula mixed according to the manufacturer’s directions and
applied and monitored accordingly using common sense.

A fertilizer nutrient stock solution will be mixed in the reservoir and
used to "cauterise" or "burn-in" the plastic components and media for half
a day to reduce any chance of phyto- or other possible bio-toxicity and to
condition and prepare the media. The solution will then be discarded on
ornamental plants & the system rinsed repeatedly with water.

Plants will then be planted in the tray and grown to hugeness.

Chapter #28: Gravimetric Cost-Reduced Redundancy Optimized
Hydroponics!

One of the most simplistic, productive, and energy-efficient
hydroponics technology implementations I have ever seen was a complex in
which gigantic, humongous plants were grown in plastic-lined troughs which
were filled with "organic" substrates.

The troughs were constructed from wooden planks and plastic liner in
such a manner as to accommodate being filled with a mixture of Pearlite,
Dolomitic limestone, and Vermiculite. A complete hydroponics fertilizer
nutrient solution formula was intermittently mixed and cycled through the
troughs to feed and moisturize (hydrate) the plants. This was accomplished
using gravity alone by having one end of the trough raised slightly higher
than the other end. At the elevated end, a reservoir was situated which
was refilled with the fertilizer solution by hand once a day by carrying
it from the collection reservoir fixed at the lower end where the excess
solution would gather by means of a through-hull fitting inserted into the
trough.

The solution was delivered to the plants using an array of intertwining
poly. pipes and accompanying fittings that had holes drilled in them
accordingly.

While gains are achieved in operating a system that is very
technologically minimalist and easy to manage, you are forced to
compromise for lack of precise control over the nutrient solution
delivery. Powered pumps allow for continuously applied uniform pressure
distribution, but having to rely on gravity introduces pressure loss
according to the water mass present in the elevated reservoir which
obviously fluctuates according to cycling frequencies.

It can be argued that the expense of purchasing a continuous-duty water
pump would be negated by the ensuing reduction in physical labor
requirements and production increase possibilities attainable through
nutrient solution dispersal optimization capabilities. However, in regions
where lack of pump availability is a problem, gravimetric hydroponics
methods can be extremely advantageous.

Chapter #29: Evapotranspiration Control in
Hydroponics!

The term "evapo-transpiration" refers to a combination of
evaporation and transpiration. Evaporation is the loss of water from the
area surrounding the plants' root zone (the rhizome) whereas transpiration
is the flow of water through the plants, with water initially being
absorbed by the roots, and then some being lost through the plants'
stomata (little holes on the underside of the leaves, akin to humans’
pores for sweat). Transpiration takes place in conjunction with the
photosynthetic cycle where carbon dioxide (CO2) and water vapour
chemically combine producing carbohydrates (sugars) for energy, and
releasing oxygen and excess water vapour.

In conventional gardening and farming outdoors and in greenhouses, it
can be beneficial to control and reduce evapo-transpiration rates to
reduce water usage where it is scarce. This can also be useful in
hydroponics systems where water conservation is desired.

There are many means available to reduce water loss indoors and out
such as using plastic mulches, anti-transpirant sprays such as waxes,
misting the plants with water, and wind breaks but there must be a balance
achieved between limiting water requirements and maintaining crop
productivity and yield.

While a layer of plastic liner over the substrate will definitely
reduce evaporative losses, it could also result in damage due to an oxygen
deficiency occurring in the root zone which would reduce crop yield
potential (see our previous article on oxygen availability). For this
reason, if plastic mulches are to be used (preferably opaque white ones to
reduce algae growth and to reflect light back up towards the plants
leaves), they should be cut away from the area directly surrounding the
plants’ stem and roots to allow for air exchange and oxygen replenishment.
We recommend using a permeable cloth such as landscape fabric which will
reduce evaporation significantly, while allowing for the roots to
"breathe".

Cuttings and transplants can gain from the use of clear plastic or
glass humidity domes and/or anti-tranpirant sprays that help to prevent
shock inset due to water loss. These allow for faster acclimatisation to
their new growing environment, but care should be taken to avoid stifling
the plants. Another method that has been proven to be effective is to
prune some of the larger leaves off of the cutting or transplant.

Chapter #30: Hydroponics Zone
Gardening!

A radical new next-generation style of hydroponics gardening in
"zones" may prove to be one of the most groundbreaking and optimally
efficient systems ever developed.

The technique involves using trough-style growing bed trays stacked and
aligned in such a manner as to allow for gravity-fed moisturization of the
crops. See the minimalist illustration.

We recommend using cheap gutters or hand-built wooden canals lined with
appropriate polymer membranes. The trays can then be mounted using hangers
(brackets) attached to metal, polymer, or wooden support structures.

The "A-Frame" technique has also been adapted very successfully using
Aeroponics growth principles by having the frame support a "skin" with
holes in it for supporting plants which are misted from inside and the
nutrient solution is re-circulated.

The system’s plumbing can consist of polymer through-hull fittings,
pipes, tubing, hoses, clamps, washers, grommets, and usually an efficient
and reliable water pump.

Perlite (Pearlite) and/or Vermiculite, Coir, Dolomitic (Horticultural
Grade) Limestone, and many other media may be used as the substrate for
the plants roots.

Many people prefer using the Nutrient Film Technique ("NFT") to
eliminate the necessity for using substrate media at all where the
fertilizer nutrient solution mixture is fed through the trays at such a
rate that a film of the liquid constantly circulates over the plants
roots. This film must be kept thin to allow for maximal oxygen diffusion.
. The recommended values for thickness and flow rate are 0.4-1.9
liters/min. @ 0.5mm-1.2cm film thickness (1:35-1:45 grade slope) with each
run before fresh nutrient addition being ~<=20 feet.

The "growth-plane" can be sculpted and manipulated to allow for
maximisation of light absorption capabilities. Light photon intensity
uniformity is usually sought after for productivity potential
optimisation.

This technique has been proven to be most effective and productive for
growing short plants like lettuce or spinach in places such as greenhouses
where ample diffuse lighting is available.

Artificial lights can be hung where artificial lighting is the
predominant source available for photosynthesis necessitating the use of
supplemental lighting.

Chapter #31: Hydroponics Viruses, Bacteria, and
Fungi!

Viral ,bacterial, fungal, and/or other biological invasions (like the
infamous Tobacco Mosaic virus and the well known Pythium spp. to name a
couple) are some of the most frightening things to both professional and
amateur gardeners everywhere around the world. They are the root cause of
millions of dollars worth of damage occurring each year and result in the
destruction of many crop and ornamental plants.

Many strains of plants have been developed that are resistant to
prevalent strains of possible micro- and macroscopic invaders, but
problems can occur with many species. Preventative maintenance,
cleanliness, and diligence can help to reduce the risk of incursions from
happening.

Sand filters are used in many places to "quarantine" sections of some
Hydroponics facilities, preventing destructive viral transmissions between
different sections of the crop plants being grown. The fertilizer nutrient
solution is re-circulated through trays or pipes filled with fine sand
that serves to allow for viral isolation and eradication. Sand filters can
thusly be used in a combination de-nitrifying/anti-viral manner.

It is always a good idea to practice using clean, porous growing media
substrates such as Pearlite or Coir to prevent harboring fungal &/or
bacterial colonies. The internal matrix structure of Perlite makes it have
very beneficial physical characteristics such as; well-balanced water:air
holding ratio capacity, light weight, and relatively high capillary force
potential.

Ozone (O3), hydrogen peroxide (H2O2), and ultra-violet light (~)
applying devices are sometimes used to guard against pests by certain
people, but they can have unwanted side-effects like fertilizer nutrient
degradation and toxicity.

Steam treatment is the preferred method of media cleaning because it is
non-toxic and environmentally friendly, yet very effective.

Copper-sulph(f)ate can also been used in solution to fight fungi, but
may result in harm to certain types of plants like Bromeliads (Epiphitic
"Air-Plants").

Disinfectants and anti-fungals/virulants/biotics such as soap, sulfur,
Mercuric chloride, alcohol, Benzalkonium chloride, Sodium hypochlorite,
Silver nitrate, Calcium peroxide, Calcium hypochlorite, and Potassium
permanganate can also be used on selected plants, substrates, solutions,
cuttings, seeds, clones, tools, and surroundings beneficially to eliminate
uninvited guests, but many are poisonous and should be avoided or handled
respectfully to avoid problems.

There have also been recent rumours of beneficial bacteria &
various other types of micro-organisms being developed and bred through
hybridization and genetic engineering (biotechnology) that are able to
diminish unfriendly pathogens such as specialized Fungi species capable of
destroying Dandelions, and others such as Mycorrhizae which aid in
nutrient gathering.

The implications are mind-boggling to say the least.

Chapter #32: Hydroponics Plastics!

According to the substantial evidence documented and available for
viewing at

http://www.livrite.com/plastic.htm

http://www.foodscience.afisc.csiro.au/

http://www.greenpeaceusa.org/media/factsheets/poisonplastic.htm

http://www.greenpeace.org/pressreleases/toxics/1999dec82.html

, and

http://www.turnertoys.com/PVC_framepage1.htm

certain types of polymer plastics such as Poly-Vinyl Chloride (PVC) and
others can potentially contain and subsequently release possibly harmful
chemicals such as Chlorine (Cl), phthalate, and "xenoestrogens" into their
surroundings. The rate of diffusion increases proportionally with the
ambient temperature. These chemicals are added during production to
increase the plastics’ desirable physical properties such as durability,
elasticity, and malleability. PVC is supposedly also hard to recycle.

Some would argue that people growing edible plants using Hydroponics or
Aeroponics or whatever should obviously use suitable substances for the
growing units.

In contrast, people growing strictly ornamental plants such as Orchids,
Roses, Peonies, Grasses, Privet Hedges, Oaks, certain vines, or what have
you can don’t have to be so concerned about the substances used to grow
their plants.

The myth that "specialized" plastics may be hard to acquire is simply
that. Many companies manufacture "food-grade" polymer lining materials.

The truth is that many plastic polymers are inert and virtually
impervious to degradation, which is the reason that they have become so
popular for use in the production and manufacture of everything from
wading or "paddling" pools to water bottles and straws.

It has also been said that most "virgin" plastics may host inherently
toxic substances.

Chapter #33: Back 2 Basics!

Hello, this month’s Hydroponics gardening article will begin a fully
graphically integrated retrospective journey into the most popular
automated Hydroponics methods currently being applied throughout the World
producing healthy, fast growing crops and ornamental plants. This is the
first in a series of six or seven pieces that will demystify Hydroponics
gardening processes revealing the basic underlying fundamental principles
involved.

The six main Hydroponics schemata are; the "raft" or "pool" technique,
the wick method, the "ebb & flo" configuration, the nutrient film
technique or "NFT", the drip array style, and the futuristic application
of aeroponics technology. There are of course many other variations
imaginable, and more simplistic methods such as growing plants in troughs
or containers and feeding them manually.

One of the easiest of the different types of hydroponics fashions to
apply is the raft technique where plants are grown on a floating raft, or
other support structure such as rigid plastic or netting, over a reservoir
of fertilizer nutrient solution. The plants’ roots are allowed to grow
into the solution where they can selectively acquire necessary nutrient
ions for biomass production. The nutrient solution is usually aerated
using an air pump to increase the available oxygen required for cellular
respiration to increases yields.

Here is a basic graphical representation of how the raft system is made
up:

The raft system can be advantageous due to its simplicity in
construction, but variables such as nutrient solution management control
and restricted oxygen availability to the plants’ roots can cause
problems.

The relatively high nutrient solution to plant volume ratio involved
can be both beneficial and detrimental as the large quantity of fertilizer
solution can act to buffer pH, temperature, and nutrient levels well, but
monitoring and concentration (TDS or EC or ppm) testing are usually
required regularly unless batch dumping is applied frequently which
imposes the problem of regulating runoff into the environment.

Chapter #34: Back 2 Basics Part Deux!

This week’s installment in my continuing series of articles explaining
the main different varieties of Hydroponics techniques developed
throughout history and in use today around the Earth will focus on the so
called "Wick" systems and their means of implementation.

The Hydroponics wick configurations bare similarities to the raft
setups (see my previous article "Back 2 Basics") in that the plants are
suspended in support materials such as nets or plastic barriers above a
reservoir of the fertilizer nutrient solution mixture that supplies the
plants with the required necessary essential ions that they need to grow.

The difference between the two methods is that the raft technique
allows for the plants’ roots to soak directly in the fertilizer solution,
whereas the wick method usually envelops the plants’ roots in conventional
growing media like Perlite (or Pearlite) or Sphagnum Peat-Moss or gravel
or sand or Coir or whatever in isolation above the nutrient mixture and
uses a hydrophilic (water attracting) media such as organic or synthetic
polymer or natural fiber rope or felt as a wick to draw the nutrient
solution up to the plants’ roots against gravity via capillary action.

Here is a diagrammatically minimalist depiction of how a wick system is
put together:

The benefits of this system are increased oxygen levels in the root
zone without the necessity of additional air pumps, and automation of
nutrient delivery in the absence of electrical liquid pumps. These
advantages, along with the relative simplicity in design make wick systems
very efficient and popular among many hydroponicists.

As with the raft systems discussed earlier, the relatively high
fertilizer volume to plant mass ratios involved can be both advantageous
and unfavorable as the relatively large reservoir of liquid nutrient
mixture can act as a buffer for environmental variables, but this can
complicate monitoring and control. Methods such as automation using float
valves or siphons to regulate solution levels and allow for volume
reduction are often used to increase the ease of execution, and these
methods will be discussed in an upcoming article.

Chapter #35: Back 2 Basics Part Três!

The focal topic of this month's Suite101.com Hydroponics Gardening
article will be a frothy and informative discussion of the myriad of
approaches utilised to consummate the hydroponics gardening technique
generally referred to as the "drip method".

This method is characterized by having some tray(s) or other
container(s) used to hold the growing media or substrate to provide
structural support of the plants’ roots into which the ionic fertilizer
nutrient solution is dripped via poly. tubing or pipes from a stock
reservoir. The dripping furnishes the plants with essential hydration and
atomic compounds enabling them to build their structures and produce fruit
or vegetative growth, depending.

The nutrient solution supply chain can consist of such things as simple
poly. hoses with holes drilled in them, or pre-formed manufactured
horticultural drip lines, or sweat-soaker hoses, etc. that are usually fed
using a simple and efficient submersible pump sitting in the nutrient
tank. Any excess nutrient juice that the plants don’t use is returned to
the reservoir using thru-hull fittings and hoses or tubing. The level of
any latent solution left in the containers can be adjusted according to
the positioning of the return fittings.

The drip system allows for quick and easy modularization by allowing
for one reservoir to be able to supply the nutrients for many planting
"zones", although it is always preferable to have more than one supply of
fertilizer solution available just in case one batch ends up being
contaminated or improperly monitored and adjusted resulting in nutrient
imbalances.

Here is an unsophisticated illustration of a drip irrigation
system:

Drip systems can be moulded into some of the most water sparing and
efficient techniques possible as the nutrient solution can be aimed
directly towards the plants’ roots without any wastage.

One common problem with these systems is that toxic salts can build up
in the rhizome causing plant damage and bio-mass production ratio
reduction. This consequence can be avoided by performing routine flushing
on a regular basis to wash away any unused fertilizer ions.

Chapter #36: Back 2 Basics Part Vier!

This article will explain the basic fundamental principles involved
with the hydroponics method normally referred to as the "ebb & flo(w)"
or "flood (fill) & drain" technique.

The "ebb & flo" method can be one of the most simplistic types of
hydroponics gardening styles to implement and control because of it’s
intrinsic unsophisticated nature. This comparative ease of application
should not mask the possible beneficial production advantages.

The basis for these systems is to have (a) growing tray(s) or
channel(s) that hold(s) the growing media into which the fertilizer
nutrient solution is forced using gravity or an appropriate pump. This
influx of ion-rich liquid subsequently forces air out of the growing media
and when the pump stops, the nutrient drains out to a level determined by
the relative positioning of the transfer fittings with fresh oxygenated
air being sucked back into the substrate. The nutrient juice flow is
cycled using a timer adjusted according to the specific growth stage
requirements and atmospheric conditions present.

The exact liquid levels achieved are dependent on the placement of the
fill & drain fittings as seen in the series of diagrams.

The 1st diagram represents a system in which there is only 1 fitting
where the nutrient is pumped in to a level determined by the power of the
pump, and when the pump shuts off, all the nutrient is allowed to drain
out.

The next picture shows the same basic setup, but a "riser" is attached
to the fill/drain fitting to keep a certain level of liquid in the tray.
This can be used where infrequent waterings are desirable, but less
concentrated solution should be used to prevent toxicity if the level is
allowed to decrease greatly due to evapo-transpiration.

The 3rd diagram shows a system where a second fitting is used to
control the maximum level to which the pump is allowed to raise the
solution before it is drained.

The 4th drawing is basically the same as the 3rd, but the drain level
is increased as with graphic #2.

The last representation exhibits a style where, according
to the fittings used, a given amount of nutrient solution is expelled each
cycle. This allows for use of fresh fertilizer each time, thereby
decreasing the risk of imbalances, but the cost is accounting for
environmental runoff. This runoff should be managed as with used nutrient
solution from a recycling system where the excess solution should be used
to fertilize other crops to prevent environmental damage.

Chapter #37: Back 2 Basics Part V!

The hydroponics method normally referred to as the "Nutrient Film
Technique" or "N.F.T." is a somewhat popular technique in which specified
plants are grown in troughs or trays or gullies. These structures are
aligned in such a manner as to allow for ionic fertilizer nutrient
solution to be pumped in to one end of the system and subsequently flow
over the plants’ roots in a thin film. This film constantly circulates
over the plants roots providing them with the required nutrients for
growth. The film thickness is optimally very thin (0.5mm-1.2cm) in order
to increase the ease with which oxygen can penetrate to the plants’ roots
via osmosis.

Certain people have a preference for using N.F.T. over other methods in
order to do away with the usual requirement for using media to support the
plants’ roots.

The nutrient solution flow rate, slope, and distance before
re-circulation and injection of "fresh" fertilizer nutrient solution of
the trays must also be monitored and adjusted. This is to allow for proper
nutrient and oxygen uptake by the plants. The recommended values are
0.4-1.9 liters/min flowing over a 1:35-1:45 grade slope with each run
before fresh nutrient addition being ~<=20 feet according to industry
resources.

Please take a look at the accompanying diagram that illustrates the
basic building blocks of a simple N.F.T. system.

People typically use flat-bottomed trays to increase the ease of
achieving uniform thickness in the nutrient film.

The beneficial aspects of the N.F.T. system are, as mentioned earlier,
the elimination of the necessity of using growth media, as well as the
supposed increase in oxygen availability to the plants’ roots. Without
proper planning and monitoring these advantageous properties can be voided
by fluctuations in the system parameters. Exact flow rates and film
thickness can be very complex, intricate, and thorny aspects to
control.

Chapter #38: Back 2 Basics Part Seks!

This edition of our periodical monthly hydroponics articles will deal
with the fascinating and ever-more popular hybrid crop production
techniques collectively known as Aeroponics.

Aeroponics refers to a plethora of various methods where growing plants
have their roots suspended in the air, and their essential nutrients and
hydration is supplied via miniscule water droplets that permeate the
closed atmosphere. This is usually achieved by suspending the plants above
a mist chamber into which the plants’ roots are allowed to enter. Inside
the chamber, a reserve of ionic fertilizer nutrient mixture is atomized
using re-circulating pumps with attached misting nozzles, or spinning
water agitators, or more recently ultrasonic buzzing devices. There are a
myriad of different designs possible that will function properly according
to circumstances.

Please check out the simplified schematic that depicts a "cloning"
chamber that was built using a cheap poly. utility tub and lid, inside
which was placed a "fish-pump" with an attached misting nozzle used to
fill the chamber with nutrient-rich water droplets. Small holes were cut
in the lid of the chamber and a layer of appropriate poly. film with slits
cut into it was placed on top to allow cuttings to be inserted into the
top of the chamber. This unit was tested and was shown to be able to
produce remarkably healthy "clones" much more quickly than with
traditional techniques in soil or soil-less mixes.

The main benefits of using the aeroponics method include the ability to
reduce or eliminate the need to use media or substrates to support the
plants’ roots (as with NFT), the markedly improved growth rate due to
oxygen availability to the plants’ roots, and the increased reduction in
transplant shock achievable.

The drawbacks of the system include complications due to water droplet
size and air:water ratio variability where plant dry weight production can
be reduced if droplets are too big or too small, and the need for having
watering schedules optimized. In the latter case, many units can use the
always-on technique, or they can experiment to achieve the best rates of
on and off times according to their situation (plant size, number, growth
stage, etc.).

Refer to our previous article "Electronic Ultrasonic Aeroponic
Fogaponic Nutrient Delivery" for more info. and links.

Chapter #39: Back 2 Basics Part 7!

The term "sub-irrigation" describes the vast numbers of hydroponics
growing methods which focus on increasing their production efficiency by
delivering the required nutrient solution directly to the plants' roots;
"sub" referring to the application occurring under or below the media
surface (in the rhizome).

The delivery of the solution directly to the plants' roots can
dramatically decrease the amount of water lost through evaporation,
thereby increasing the dry weight to evapo-transpiration production yield
ratio.

Many different styles of hydroponics growing fashions involve
variations of sub-irrigation techniques and could be classified as such,
but this article is specifically oriented towards describing the use of
such items as "soaker"-hoses, drip-lines, etc. that are implanted below
the surface.

Sub-irrigation systems are usually designed in a similar way as to the
previously described hydroponics drip systems in that the delivery
apparatus is designed to move fertilizer nutrient solution from a
reservoir to the plants roots as efficiently as possible. This usually
involves the use of a pump and various types of delivery lines. Please
refer to the diagram that shows a basic configuration.

Recently polymers and other new materials have been developed that
allow for inventions such as micro-pore tubules and precision drippers
that can be useful depending on circumstances.

The main benefits of using the various sub-irrigation techniques are
the increased water conservation potential requirement during nutrient
delivery and the ability to have optimal control over nutrient and water
utilization.

Drawbacks of sub-irrigation arrangements can be the variability in
uniformity with time due to sub-surface root blockage and salt buildup,
and the detrimental implementation complexity associated where large plant
numbers are to be grown. Some manufacturers are supplying emitters that
have been treated with pesticide to prevent root blockage. Blockage can be
prevented using mechanical barriers and maintenance.

Sub-irrigation can also be difficult when using any insoluble or
particulate or organic nutrients and/or supplements due to the possibility
of clogging occurring.

Back 2 Basics Part Eight! Aeroponics²

Good Day! Welcome fellow hydroponicists to this month’s exciting
article that will delve further into the realms involving the principles
of modularity and aeroponics techniques used for growing fabulous plants
be they edible, ornamental or other!

In our previous articles "Back 2 Basics Part Seks!…" and " Electronic
Ultrasonic Aeroponic Fogaponic Nutrient Delivery" we dipped into the world
of aeroponics growing and also explained the basics of how to build simple
individual growth chambers that could be exploited to aid in the process
of "cloning" plants or used in the growing of plants to full maturity. Now
we will expand on those thoughts and re-introduce the concept of modular
extensions that can allow for astronomic increases in efficiency and
productivity using a simplistic systematic approach.

The basis for modular expansions is the use of a central ionic
fertilizer nutrient solution reservoir that is used to feed any number of
modules, these modules being the trays or containers that the plants
and/or media substrate are housed in.

Please feel free to take a moment out of your busy schedule to peruse
the accompanying graphical representation of the building blocks of a
modular aeroponics unit (note the similarity of this picture to some of
our previous illustrations, this resemblance is not at all by random
chance, we have purposefully repeated the modular conceptual theme to
emphasize it’s usefulness). The reservoir exhibited below the growth
chamber would be filled with nutrient solution and the solution
subsequently pumped under pressure through hoses and/or tubes to the
misting/atomizing/fogging nozzles that would disperse the fertilizer via
droplets in the atmosphere for the plants’ roots to absorb. Any excess
liquid would then be returned to the reservoir via more hoses and/or tubes
and fittings. The solution would be topped-up, refreshed, and monitored
regularly to maintain optimal growth conditions for the plants.

Hydroponics Nutrient Solution Delivery
Methodologies!

The selection of drip, mist, sub-irrigation, and other water-saving
horticultural equipment available has grown at an incredibly rapid pace in
recent years it seems.

Many (in fact, an increasingly massive plethora of) different types of
drippers are available commercially, as well as innumerable styles of
misters, atomizers, sprayers, seepers, sweaters, foggers, diffusers,
gushers, and the like.

Here are a few links from our virtual cornucopia:

http://www.dripirrigation.com/

http://www.dripworks.com/

http://www.raindrip.com/

http://www.kesmist.com/

http://www.irrigro.com/

http://jessstryker.com/install.htm

http://www.dripirr.com/

http://www.netafim.com/netafim/doa_iis.dll/Serve/level/english/1.4.html

http://www.polydrip.com/

http://www.dripworksusa.com/

http://www.greene-eden.com.au/

http://huskysearch.cs.washington.edu/

http://www.northernlight.com/

http://www.beaucoup.com/

http://www.google.com/

http://www.infind.com/

please feel to visit one, some, or all of them should you desire. We
would appreciate it if you would send us any valuable links to other sites
that you may have come across in your travels.

Some water delivery apparatus such as the aforementioned drippers, etc.
that can enable incredible water efficiency may also have the tendency to
be troublesome because of the practically inevitable clogging that can
occur in certain cases due to salt buildup or foreign material or algae.
Some innovative types allow for regular preventative maintenance (PM) such
as cleaning that can allow for more control over a regular, more uniform
flow rate. Many sorts also require that high pressures or gallons per hour
(GPH) criteria have to be met in order to assure proper functioning.

People have been known to make their own "drip-line" using plastic
tubes and a drilling machine.

New developments on the field include the introduction of such devices
as ultrasonic transducer atomizers, micro-tubules, semi-porous membranes
among many others.

Top 10 Reasons to Add Peat Moss, Coconut Coir, etc. to
your Perlite(Pearlite)!

Perlite(also known as Pearlite) has become known as one of Nature’s
most beneficial, efficient, productive, and economically viable growth
substrates for plants around the world. As described earlier in our
article "Perlite! Pearlite! Rah! Rah! Rah!" Perlite is derived from
volcanic rocks that puff up when heated similar to the way popcorn does
when it is cooked. These puffed rocks have incredible surface area to
volume ratios making them very useful in a horticultural context. The ore
material for Perlite is present in many locations around the world in
great abundance making it cheap.

Perlite has the intrinsic characteristic of having an excellent water
to air holding capacity that allows for frequent watering while
maintaining a predictable moisture content. This physical trait can even
buffer out the effects of over-watering when proper drainage is applied.

Perlite by itself is not always the most suitable of substrates for all
plants or circumstances, and that is where this article will help to shed
some light into other types of amendments to add when necessary and why.

Top 10 Reason to Add…to Your Perlite:

Sphagnum Peat Moss-Another natural product which can help by increasing
the Cation & Anion Exchange Capabilities (CEC & AEC) of the media
which increases the nutrient adsorption holding capacity(1). Peat can also
add lots of trace minerals & nutrients(2), along with humic acids(3).
Vermiculite-Yet another very plentiful natural product that can increase
the CEC & AEC as well as adding Potassium & Silicon. It can also
increase the water-holding capacity of the media if so desired(4). Sand
can be added to increase drainage(5) or to decrease air volumes in the
media(6). Coir can be added to increase moisture-holding properties, as
well as to acidify the substrate where applicable, as with Peat(7).
Shredded or pulverized algae &/or seaweed can be put in to add many
beneficial enzymes, catalysts, etc.(8). Organic Humus & compost can be
thrown in for many of the above reasons, as well as to increase the
rhizobial carbon level(9). All these amendments plus numerable others are
also added to increase the heterogeneity (as opposed to uniform
homogeneity) of the growth substrate(10).

Hydroponics Cation & Anion Exchange Capabilities
(intro.)!

One of the great mysteries of the universe that has been elucidated by
modern-day chemists, horticulturists, and other scientists is the wondrous
intrinsic capability that certain compounds exhibit which allows them to
adsorb (that's right, aDsorb!) other ions and molecules onto their
surfaces. In an agricultural context, this allows for a greater
understanding of the processes by which nutrients are stored and
distributed in rhizobial regions (around the roots).

Adsorption is basically defined as the physical attraction between two
separate bodies, allowing for one body to be held on the other's surface,
kind of like the way a balloon will stick to a wall after you rub it on
something hairy, like a cat or dog. This attraction technically involves
electrical (electrostatic) charges and magnetic fields, etc. and is
quantified according to charge capacity. Different types of soils and
natural or synthetically produced soil-less plant growth media
constituents (like clays, organic matter, zeolites, etc.) can have a net
positive or negative charge on their surface due to differential ionic
substitution during their formation making them colloidal. These charges
allow for the substances to gather a certain amount of complementary and
oppositely charged particles on their surfaces. Without getting into the
sub-atomic nuclear physical relationships between the quarks and neutrinos
involved, depending on the pH (acidity or alkalinity) of the sample, the
net charge available can vary a great deal due to variations in ionic
concentrations.

A Cation is defined as a positively charged ion (in solution for our
purposes), such as Calcium (Ca2+), Potassium (K+), Magnesium (Mg2+), et
cetera.

An Anion is defined as an ion that has an overall negative charge,
examples being Sulph(f)ates, Phosphates, and the like.

Thus, the acronyms CEC & AEC were coined for Cation Exchange
Capability and Anion Exchange Capability respectively in order to describe
the relative levels of attractive forces attributable to samples with
differing charge types.

For more info, please visit these juicy web sites:

http://www.agronomy.psu.edu/Courses/SOILS101/lectures/Clay/ClayIndex.html

http://soils.ag.uidaho.edu/soils205/notes/notes09/Notes09.htm

http://syllabus.syr.edu/esf/rdbriggs/for345/cation.htm

http://www.gsaresources.com/cationexchange.htm

Hydroponics Colloidal Organic Matter!

Believe it or not, actual organic matter can be used beneficially in
hydroponics gardens in a manner that can dramatically increase the
colloidal partition of the growing media, thereby increasing its nutrient
storage capability. Many organic materials also exhibit incredibly high
surface area to volume ratios which allow them to act as very efficient
nutrient "sponges" or "batteries" or "reservoirs".

Organic substrate constituent candidates such as Coir, Peat-Moss, Kelp,
bark, alga, Crustacean compost, grape rinds, coffee grounds, etc. are
readily available in bulk in many regions around the world and some are
actually considered as being waste materials. Many of these substances can
be used in hydroponics growing beds to not only increase the advantageous
physical characteristics of the rhizome (by increasing moisture retention
capacity, etc.), but they can also release nutrients upon their own
inevitable decomposition, giving the old "double-whammy" if you will.

Organic materials can also help by introducing and supporting
beneficial bacterial inoculation, such as Rhizobium spp., Mychorizzae
spp., etc. which can act to further aid in nutrient acquisition by the
plants' root system, but they can also be harbingers of disease if they
have come in contact with certain strains of moulds or viruses that can
adversely affect many plant species such as Black Spot and the infamous
Grey Fuzz.

Indoor Hydroponics Moss & Algae
Gardens!

***CAUTION: Indoor Hydroponics Moss & Algae ("Boggish") Gardens
should not be grown in certain areas where harmful Fungi, Moulds, etc. may
grow!***

Hello & Happy Canada Day to You! This month’s hydroponics article
here at Suite101.com will give a detailed description of how you can build
your very own indoor hydroponics Moss & Algae garden. Indoor
hydroponics Moss & Algae gardens are apparently going to become very
popular among the elite and contemporary visionaries.

Check out this picture of a portion of a recently built indoor
hydroponics Moss & Algae garden. Please note the grass which
infiltrated the garden, it is being allowed to live…for now!

This garden is obviously in it’s infancy, but there appear to be many
species of mosses already starting to grow in it (like a total plethora,
if you will) and it will flourish abundantly as long as it is kept moist
and enough light is supplied.

The original patch of moss was harvested from a backyard here in
Ottawa, Ontario, Canada. It appears to be quite a healthy sample
containing mostly Sphagnum Peat Moss. A few of other types of Mosses &
Algae are starting to colonize the tray as well.

This indoor hydroponics Moss & Algae garden was built based upon
using the "ebb & flow" technique as described in our previous article
"Back 2 Basics Part Vier!".

Here is a graphical representation of the basic building blocks of this
system to refresh your memories.

This hydroponics systems consists of the incorporation of a simple
plastic lined tray which is sitting on a support (pails) and the tray has
1 hole drilled in it to allow for liquid nutrient fertilization solution
to be injected and then subsequently drained using a cheap multi-purpose
utility pump.

The tray is filled with 2-4" of Perlite (Pearlite) and Vermiculite @ a
1:5 ratio, with some extra Vermiculite spread on the surface to encourage
infestation of native species of algae and mosses. Some powdered Dolomitic
Limestone was also added to balance pH & supply additional benefical
Magnesium & Calcium for the Mosses and Algae.

The light source consists of 2 4 foot 40 Watt fluourescent light tubes,
one full-spectrum & one not-so-full-spectrum, which cost a total of
~$6 plus the fixture which is a traditional economy utility type that is
hung from chains attached to hooks screwed into the ceiling beams.

The nutrient solution being used is a professional-grade full-spectrum
fully soluble hydroponics formula which we mixed in @ ½ strength and don’t
plan to change more than 1ce a month. We don’t plan to bother checking the
pH either.

We will keep you updated on the progress of this garden with regular
digital picture updates, we may even have a contest to identify which
species of Mosses and Algae are present.

Bog Action!

***CAUTION: Indoor Hydroponics Moss & Algae ("Boggish") Gardens
should not be grown in certain areas where harmful Fungi, Moulds, etc. may
grow!***

And the battle rages on, ever more vigorously, in this no-holds-barred
battle-of-the-species fight-to-the-finish. Alga versus Moss, Moss versus
Lichen, Lichen versus Fungus, it’s like a big bog mayhem jamboree in
there. Many different types of freakishly diversified species have
emerged, but who or what (or even which for that matter) will emerge
victorious as the dominant organism? If they had teeth & nails, they
could be described as to be fighting tooth-&-nail, but they obviously
don’t.

At this point, the Black Goo is making gains on the lush green
carpet-like masses, while the leafy spreaders(see pic’s) and fuzzy
mountains are making their ins as well. The "Little Pine Trees" are
running rampant over the wild, untamed nether-regions.

To cast some light & dwell upon the technical aspects of this
"Boggish" garden for a moment, I have changed the fertilizer nutrient
solution once, just for fun, as well as continuing to refrain from
bothering to check the pH, because that would be redundant when I don’t
really care what grows in my garden, just as long as something does, and
can thusly allow the pH to fluctuate wildly if it will with no restraint.
If nothing were growing, or if my plants, etc. looked like they were not
enjoying the soil media particularly, I would probably check the pH. If my
pH were to be "off", I would likely do a soil media pH test by soaking it
in a water sample with known pH to see if I could possibly adjust my mix,
or add additional amendment constituents to balance its
acidity/alkalinity(basicity). The truth be told, I have confidence from
previous experience that my mix of Perlite(Pearlite), Vermiculite(from the
Latin for Worm), Sphagnum Peat Moss, Dolomitic limestone, & Algal
remains is very well pH buffered and consistently uniform in overall
performance.

Upcoming articles will deal with benches, alien invaders, and weird
stuff you might find in your reservoir.

Mould, Powdery Mildew, Fungus Gnats, & Jumping
Spiders!

***CAUTION: Indoor Hydroponics Moss & Algae ("Boggish") Gardens
should not be grown in certain areas where harmful Fungi, Moulds, etc. may
grow!***

This will likely be the last report for a while on the on-going growth
& succession of my "Boggish" garden due to the fact that I plan to
focus on a more diverse variety of topics to be featured in upcoming
articles. Please don't worry there will be updates in the future at some
point.

As you can plainly see from the pictures below (which were taken using
a cheap digital camera with a magnifying lens in front of it), there
appear to be multiple species of mosses, possibly some
saprophytes/epiphytes, and/or algae and plants in my garden that seem to
be flourishing abundantly. There is also an infestation of Fungus Gnats
which has been left untreated by any means until now, but they may have
been subject to predation by a certain little jumping spider that has
managed to elude my camera iris for now. The Fungus Gnat population seemed
to peak and bloom into a large population at one point which appeared to
be uncontrollable, but they have since died off in a sudden population
crash, likely due to lack of resources such as an adequate and regular
supply of food. The black mould also seemed to be spreading wildly leaving
patches of dead moss in its wake, but then some white powdery mildew began
growing on the black mould, how ironic.

I have been watering the tray less frequently as of late (approximately
once every 4 to 5 days now as compared to every second day with generous
amounts of misting before) to try to reduce the surface moisture level to
ward off too many species of mould and fungi. The pH values of the
nutrient solution and growth media(a mix of vermiculite, peat,
perlite(pearlite) and dolomitic limestone) have not been checked, but the
plants, etc. appear to be healthy. The nutrient solution has however been
topped up with fresh water regularly.

I have increased the amount of simulated daylight that my garden is
receiving from it's two 4 foot 40 Watt fluorescent light sources from ~14
to ~18 hours per day which has resulted in an increased growth rate of the
plants, mosses and algae

Check It!

Check- (also known as one-way flow or anti-siphon or back-flow
protector/preventing) valves are devices that are engineered to allow for
unidirectional flow control over liquids or gases. These valves are
typically placed in-line with conventional delivery tubing or piping.
Check-valves come in many different styles, sizes, and materials.

Please check out the basic block-diagram graphical representation of a
check-valve configuration below. Many other variations are conceivable,
including those where springs are placed in opposition to the flow plane,
allowing for both pressure regulation and directional flow control using
only one device (i.e. killing two birds with one stone, as it were)!

In hydroponics gardens, these valves can be used to control the
nutrient solution and permit it to move only in one desired direction
while inhibiting reverse flow the opposite way. This can be of great
benefit where reservoirs are required to be filled on a repetitive basis
for fertilizer nutrient solution storage, such as in hydroponics beds or
trays where a minimal amount of watering cycles is favoured, or where a
basin used to supply a gravity-fed system is present. This fertilizer
nutrient storage can allow for prolonged pump life extension through
reduction in usage.

Check-valves can also be used to prevent any damage from occurring due
to the unwanted siphoning of nutrient solution into air pumps that are
kept below the reservoir solution surface level.

These valves can be used in place of secondary regulated return lines
to reduce initial capital expenditures. "One line" systems can require
increased initial setup time to verify that the input pressure & flow
rates are tolerable and within specified operating margins in order to
prevent mishaps such as tray or reservoir overflow or pump problems.

Here are a couple of links you might want to check out to decrease your
ignorance on the topic of check-valves:

http://www.flocontrol.com/check.htm

http://www.netafim.com/netafim/doa_iis.dll/Serve/item/English/1.4.5.1.4.9.html

Helllooooooo Poly. Pt. Deux!

Hello fellow hydroponists, this month’s spooky article will pertain to
the use of polymers and plastics in the hydroponics industry. As alluded
to in our previous article "Hellooooo Poly!" people should always be
careful to choose the proper materials when constructing trays or
reservoirs or other types of structures that will be used in hydroponics
systems to grow plants. Precautions should especially be taken where
edible plants that will eventually be eaten by humans or other organisms
(such as cows for instance) are to be grown, in order to protect the
eater(s).

Many plastics that are not manufactured under regulatory guidelines
relating to food contact can contain hazardous chemicals and metals such
as Copper that can migrate or leach into the surrounding environment. If
edible plants are grown in contact with these types of products or if a
liquid fertilizer nutrient solution is stored using inappropriate
materials and then used to hydrate and feed plants, the plants may become
contaminated. Although plastics are known around the Earth for their
cheapness, durability, and availability, many of them should not be used
in contact with plants that will be used for food.

The Canadian government agency known as the Canadian Food Inspection
Agency has a web-site that has information regarding these matters and it
is located at: http://www.inspection.gc.ca/ click
on "manuals" and then "reference materials".

The United States government has a web-site with similar material and
it can be found at: http://www.access.gpo.gov/nara/cfr/waisidx_01/21cfr177_01.html
and another at http://www.fda.gov/opacom/morechoices/smallbusiness/blubook.htm
. When possible, only materials that have been confirmed to be "food safe"
by the manufacturer should be used in hydroponics systems used to grow
food crops. Many different types of products such as polyethylenes,
polystyrenes, and nylons, to name a few, are regarded as being safe for
use in contact with food products.

On the other hand, when ornamental plants that are not slated for
consumption are being grown, almost any plastic that will suit the
physical parameters of the project can be used.

Hydroponics Benches, Tables, etc. or Lack
Thereof!

Indoor & outdoor hydroponics gardens of small, medium, and
respectively larger dimensions usually require the use of some sort(s) of
bench(es) or table(s) or other type(s) of support structure(s) to place
the rhizobial region at a level above the nutrient fertilizer solution
mixture reservoir to enable a gravity-fed supply-return system, unless
supports are attached to the ceiling or columns or other types of
structures, or if the reservoir is somehow sunk to a level below the
flow-line.

Support benches are often built from various types of woods such as
spruce or pine, or metals like steel or aluminium and can be bolted,
welded, or screwed together, sometimes with the use of brackets and other
types of hardware. Some of the simplest designs require nothing more than
a supply of two-by fours and posts, some plywood, a bunch of screws and
the use of a handsaw to erect. Tables or benches can be bought in kits, or
assembled from plans.

As mentioned earlier, it is also possible to eliminate the inherent
need for the aforementioned support structures by locating the nutrient
fertilizer solution reservoir physically below the flow-line level of the
growth-beds or trays by digging a hole in the ground or floor. In most
indoor areas where it is not possible (or plausible) to dig a hole in the
floor to accommodate the reservoir tank, an interesting technique that can
be employed is to use the floor as the base of the growth tray(s) and to
have the fertilizer nutrient solution mixture reservoir tank on the same
level, but to then have a nutrient return pump situated in a division of
the growth tray in addition to the input pump. These two pumps can work
sequentially to feed the plants cyclically on a timed schedule. The
nutrient solution return pump can be sequestered into it's own secondary
section of the growth tray, while keeping the growth substrate media in
the other by using a semi-permeable filter material of correct porosity.

Please take a moment to study the block diagram of a simple two-pump
supply-return system below:

The walls of this type of growth-tray system should be higher than
normal in order to allow for an increased thickness of growth media
substrate to have good drainage and also to permit the necessary amount of
fertilizer solution to be returned by the pump, as an amount of solution
will likely remain in the tray because most pumps will not be able to
remove all of it. Depending on the type of pump used, an automatic
shut-off similar to those used for sump-pumps must be used, while others
can run dry.

Note: the return line should be cut above the full level of the
reservoir or a check-valve should be used as described in one of our
previous articles to prevent siphoning of solution back into the tray.

Hydroponics Sans Table(s)!

Hello again fellow Internet hydroponicists & Happy New Year to you
all! Lets all try to make our hydroponics gardens grow more this year than
ever before!

Partially in response to the interest in our previous article titled
"Hydroponics Benches, Tables, etc. or Lack Thereof", this first
installment of our year 2002 hydroponics articles will be the second in a
series dealing with alternate (to using benches, tables or other support
apparatus(es)) means of cyclically supplying & returning the required
liquid hydroponics fertilizer nutrient solution mix respectively to and
from the area supporting the root system(s) of the plant(s) being grown.
These articles should be especially beneficial and/or enlightening to
short people and/or persons who may not want to buy or build a bench or
table to support their plants, or people who plan to grow plants that tend
to get quite tall, thus requiring that the growth-plane be lowered to
allow for the plants to mature without the necessity for pruning, if so
desired.

Please take a few moments of your time to look at the following
graphical depiction of an adaptation of the basic two-pump supply/return
system as outlined in our previous article.

As you can see by comparing the two systems, the difference between
this one and the previous setup is that some two-by-fours and plywood for
example, or other structural components, have been used to raise the
growth tray drain flow-plane above the floor level, allowing for more
complete drainage of the tray. In this scenario, a couple of fittings, a
piece of tube or hose, and some filtering material has been added to
facilitate the nutrient fertilizer solution transfer between the two
containers.

This setup allows for more complete drainage of the growth-tray. The
system, as with any, should be fail-safe tested prior to use by
over-filling with a mild fertilizer nutrient solution mixture. This will
also allow for any residues, which may be present on the tray liner,
tubes, etc. to be removed from the system.

I'm not an expert on the ancient civilizations such as the Aztecs,
Babylonians, etc. that have been reported to have grown crops
hydroponically with great success and wildly varying methods, but some of
the descriptions and diagrams of their systems that I have heard about and
seen in the past have served to inspire me to explore and imagine
different means of hydroponics nutrient fertilizer solution delivery and
return.