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This page describes the various methods used in the creation of a
hydroponic growing system.
 | GROUPS OF HYDROPONIC SYSTEMS
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| "Active" System which uses a
pump to circulate nutrient
solution to the plant roots
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| "Passive" System uses a wick
system which draws nutrients to the root, rather than relying on the pump
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| "Media Based" System,
such as the ebb and flow (or flood and drain), top-feed (drip), or bottom feed system,
which utilize various types of non-soil mediums which will be discussed later.
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| "Water Culture" Systems,
which mainly avoid media for purposes other than physically supporting the plant.
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MEDIA BASED HYDROPONICS
Ebb and Flow Systems
Ebb and flow systems can exist as either "active" or
"passive"
gardens. They work by alternately flooding and draining a nutrient bed composed of a
growing medium. This can be done either by hand or with a timer and pump. This is a simple
and popular method.
The Top Feed System
The top feed systems are "active," using a timer and pump to deliver a slow
stream of nutrient solution to plant roots, which, after dripping through a nutrient bed,
collects in the main reservoir, and is used again. This system is easy to use, yet can
also be complicated by clogged tubes.
Water Culture Systems
Water culture systems avoid the use of media, and thus the mess.
It operates "actively," as the roots continuously need to be immersed in
solution to avoid drying out.
| All of these systems can be purchased in kit form, or
constructed from various materials, such as PVC piping, tubing, and plastic cups and
trays. Additionally, one may purchase artificial lighting to allow growth in darker
areas such as basements.
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This is a picture of an eleven-piece kit distributed by Hydroponics Online
GROWING MEDIA
Although there is no soil in a media based system, the
growing roots of the plants must still be anchored. The wide range of inert materials
which can be used to support plant roots are called growing media. The hydroponic
media that work best are pH neutral, provide ample support for plants, retain moisture,
and allow space for good air exchange ( Homegrown
Hydroponics ). The type of media you choose will depend on the size and type of
plants you wish to grow, and the type of hydroponic system being used. Heydite, clay pellets, Perlite, vermiculite, and Rockwool are the most
popular media.
Photograph (courtesy of Homegrown Hydroponics)
of popular types of growing medium used to anchor plants.
Aggregate culture is
composed of chemically inert particles used to root the plant. It is usually contained in
plastic bags or containers.
Rockwool culture is composed
of molten rock. It is a fibrous material that comes formed into cubes. Most
like soil, it is fibrous and spongey. It is occasionally used in small amounts in water
culture to weight down the growing plants. According to Homegrown Hydroponics,
"rockwool provides roots with a good balance of water/oxygen." Rockwool
can be used with continuous drip or flood and drain systems.
Perlite, made from volcanic
rock, is a light white material often used as a soil additive. The pellets can be
used alone as growing medium, but don't provide enough anchorage for large plants. Perlite
is often used to start seeds, which can easily be transplanted after rooting.
Vermiculite is used the same
way as Perlite, and the two are sometimes mixed together. Vermiculite is made from
heat expanded mica and has a flaky, shiny appearance. When mixed with Perlite, it contains
very little nutrient, and is used a a soil additive, or alone as a hydroponic medium.
Geolite is a synthetic
ceramic pebble fired in a kiln. It is reusable and completely inert and sterile. Geolite,
however, does not work particulary well in "passive" systems (InterUrban Water
Farms).
Heydite, a media made from a
porous shale, or Hydrocorn, medium-sized clay pellets are best utilized in a continuous
drip system. The pebbles provide enough free drainage and air space to take advantage of
continuous feeding. These media also provide good anchorage for larger plants, and are
easy to clean and re-use indefinitely.
*****Some hydroponic systems do
not require any growing medium at all. Various methods are used to support the plants
while the roots are directly fed nutrient solution. Some examples of these are, aeroponic,
N.F.T., or Nutrient Film Technique; and deep water culture.
****Info. from various sources: Alternative Agriculture,
Inter-Urban Water Farms, Hydroponics Online, and Homegrown Hydroponics.****
Questions about this website?
Email the webmasters:
Jenny Yandell and Kristen Scioli
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