Sunday, 15 June 2008

4 Hydrophonics systems



1.Water Culture or Aquaculture
2.Aggregate Culture
4.Continuous Flow Systems


1. Water Culture or Aquaculture

The water culture method of hydroponics is the simplest to set up on a small scale. In this system the plant roots are totally immersed in a nutrient solution. The major disadvantages of this system are the large amount of water required per plant and the need to aerate the solution continuously.

The actual design of the system is limited only by the imagination of the builder. The system must provide means to (1) support the plant above the solution, (2) aerate the solution, and (3) prevent light from reaching the solution (to prevent the growth of algae).

A standard tray or tank is shown in Figure 1. The tray may be made of concrete or of plastic-lined or asphalt-sealed wood. If you use asphalt to seal the tank, be sure that it does not contain creosote or tars. Do not use asphalt that leaves an oil film on the surface of the water. A typical size is 6 to 12 inches deep, 2 to 3 feet wide, and as long as is convenient. The plants can be supported by inserting them through holes drilled in a plywood top or through holes punched in a l-inch-thick Styrofoam sheet that floats on the surface of the solution.

You can make a small system from a child's wading pool, a plastic pail, a fish tank, or a drinking tumbler. A large tomato plant should be grown in a container that holds at least 2 gallons as the solution in a smaller container will be used up too quickly. Lettuce plants, on the other hand, may be grown in smaller containers.

Short plants such as lettuce and spinach will usually support themselves. Drill a 1-inch hole in the Styrofoam or wooden cover and insert a transplant. The plant may be held in place by packing a flexible material such as cotton into the hole around the stem. A plant started in sand, perlite, or vermiculite can be transplanted easily to the water culture system because these materials can be washed from the roots readily.

Vining plants such as cucumbers and tomatoes must be supported by string. When pruned to a single stem they can be wrapped around a loosely hung string as they grow (Figure 2).
Aerate the solution continuously by pumping air through a perforated hose or pipe immersed in the solution. For small systems an aquarium pump and porous stone will work. Do not bubble the solution too vigorously because excessive movement may damage the tender roots and impair plant growth.

Change the nutrient solution every two weeks when the plants are small and once a week as they begin to mature. Add water daily to keep the solution level constant.

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