THE EBB AND FLOW OR FLOOD
SYSTEM
The flood system is the method most
people picture when hydroponics is
mentioned. The containers are periodically
flooded and then drained. Construction of a
manual unit is easy. Imagine a tray with a
flexible drain tube on the bottom. The tube
is held up in the "plug" position. Water
pours into the tray until the containers are
flooded. The reservoir, often a water jug, is
placed back into position so that it can
catch the drain water. Then the tube is
placed back into the "drain" position.
Growers often make small automated
units. First they seal the reservoir tightly.
Two tubes are attached using a bottle
stopper. One is attached to an air pump at
the other end and pushes air into the top of
the reservoir. The other tube goes into the
bottom of the reservoir. When the air is
pushed into the reservoir the water rises,
flooding the growing area. When the pump
is turned off, the water flows back to the
reservoir. More sophisticated units have a
back-flow valve. Usually gardens are
flooded twice a day using a short range
timer. Larger systems use a water pump to
flood the growing area.