Figure 3.

An ebb and flow or flood and drain hydroponic system in which nutrient solution is pumped from an external reservoir (A) over the plants at set intervals during the day. (I) During the fill stage a timer turns on the pump (B), which pumps the nutrient solution up through a pipe or tube (C), through the fill inlet/drain (D), and into the flood tray (E). An overflow drainpipe (F) sits several inches above the fill inlet/drain, and prevents the system from overflowing. (II) If the tray starts to overflow nutrient solution will return to the reservoir (A) through the tube connected to the overflow drainpipe (G). Once the pump turns off, the nutrient solution drains back down the fill tube (C), through the pump (B), and into the reservoir (G). (III) After the pump turns off the flood table (E) drains completely back into the reservoir (A) and sits empty until the next pump cycle.