What Does the Water Level Need to Be for Hydroponics?

Ebb and Flow

• An ebb-and-flow system consists mainly of a reservoir that holds the nutrients mixed with water, a pump and a plant tray. The water is pumped from the reservoir into the plant tray several times per day, then it is allowed to drain slowly back into the reservoir. The water level in the reservoir must be deep enough so that it can fill the plant tray to within an inch of the top before the end of each pumping cycle.

Rafts

• A raft system consists of a container to hold the water with a piece of polyurethane foam floating on it. Plants in the system typically grow in pots that sit in holes cut into the foam and their roots grow down into the reservoir. The actual water level for this type of system varies, but the water in the container must be deep enough to allow the plants’ roots to develop. Generally, the water level in a raft system is best kept at least 4 to 6 inches deep.

Nutrient Film Technique

• Hydroponic systems using the nutrient film technique need a reservoir that holds enough liquid to allow the pump to send a continuous flow through the pipes in the system and over the roots of all the plants. The water inside the pipes should be just deep enough to reach the plants, but shallow enough so there’s room inside the pipe for some air to reach the roots at all times. The actual water level depends on the type of pipes or trough the plants are in and how large the roots are, but the water level in the reservoir must be higher than the pump that pushes the water into the pipes.

Drip System

• In a drip system, tiny amounts of water periodically drip into each pot. The water level needs to be adequate to support your system, and this depends on how many plants you have, how big they are and whether you are using a recovery or a non-recovery type of system. A non-recovery system does not recirculate the water, while a recovery system catches any excess and uses it again. You need less water for a recovery system than you do for a non-recovery system of the same size, since there’s very little waste in a recovery system, but both need reservoir water levels that are higher than the top of the pump.