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What is Ebb and Flow / Flood and Drain?

Ebb and flow is any hydroponic system that periodically fills a tray with a nutrient solution, submerges the root zone, and drains it back to a holding reservoir for a future feeding.

The upper tray in a flood and drain system has 2 holes in it. One of the holes is used to pump a nutrient solution into the tray, filling the tray and flooding the root zone for a short period of time. The second hole is a raised drain that makes sure the tray doesn’t ever overfill. The feeding pump in the lower reservoir is attached to a timer and runs when necessary. Once the pump turns off, the nutrient solution in the upper tray will gravity feed back through the pump and into the holding reservoir below.

Pros of Flood and Drain:

  • The roots in these hydroponic systems are exposed to fresh atmospheric air every time the water drains away.
  • There is less risk for root diseases in a hot environment if the roots are only exposed to the nutrient solution periodically.

Cons of Flood and Drain:

  • If the feeding pump fails or clogs, the table above will not flood and the plants can be left without water for long periods of time.
  • Ebb & Flow tables that don’t full drain can bring problems like excess algae growth or root diseases. Make sure your trays have a proper slope to fully remove the nutrient solution after each watering.
Updated on November 11, 2019

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