Flood and Drain Hydroponics
The Flood and Drain hydroponics system or sometimes reffered to as an Ebb and Flow system periodically floods and drains the growing medium of a plant with nutrient solution. There are many hydroponic designs for this all easily adaptable to homemade hydroponics systems.
Plants are placed in a container or grow bed containing a growing medium of choice. This container should be higher than the resevoir that will feed the plants. This will allow the nutrient solution to drain easily when the pump is not running for the drain cycle.
The container the plants are in should have an inlet and an outlet for water flow. The outlet will have an "overflow" set at a predetermined hight. This will prevent the grow bed from overfilling but allow the water level in the bed to reach a hight that will cover the entire roots of your plants. Water that comes from the outlet will return to the resevoir.
A small electric pump is used to deliver that nutrient solution from the resevoir. The size of the water pump depends on the size of the grow bed / container, the size of the resevoir and the distance the water needs to travel from the resevoir to the inlet. The water pump is submerged in the nutrient solution and attached to a hose whose other end is attached to the water inlet on the grow bed. The pump is plugged into a timer set to turn the pump on and off at regular intervals throughout the day. The frequency and duration the pump turns on and off depends of a few factors.
When the timer turns the pump on, nutrient solution is pumped into the bottom of the plant container slowly flooding it until it reaches the top of the growth medium to automatically drain back down into the nutrient solution resevoir. The draining action results in splashing which aerates the solution however it would be recommended to also use an aquarium pump and airstone to arirate the water and help to keep the nutrient stirred in the resevoir.
When the pump turns off the plant container slowly drains back down through the water outlet and into the resevoir to be reused when for when the pump turns on again. As a further benefit, this draining action sucks oxygen down into the growing medium to the plant's roots to be used as needed.
In its simplest form, there is a tray above a reservoir of nutrient solution. Either the tray is filled with growing medium (clay granules being the most common) and planted directly or pots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill the upper tray with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills past the drain stop, it begins recirculating the water until the timer turns the pump off, and the water in the upper tray drains back into the reservoirs.