Backyard Aquaponics
A place to discuss aquaponics

In a flood and drain system what is the maxium time you can flood without hurting the plants? What is the maxium time you can drain before hurting the plants? My GB's are filled with gravel 10 inches deep. Please advise.

Other than not letting them dry out completely I don't believe there is a time limit. Many people run constant flood, so as long as fresh water is coming in you are fine. And as far as empty, even a few days would not hurt the plants. I turn off my pumps at night, so every night my plants sit with no water in the grow beds.

The answer is we don't know and it depends.

There are no studies that have identified ideal flood and drain times and they are probably different for different crops, stocking densities, system designs and climate.

For BYAP systems people have tried all sorts of different times with good results so it probably doesn't matter too much as long as you are not pushing things too close to the line with your stocking density.

If you are going to run an auto siphon in the GB then the diameter of the standpipe in the siphon will determine the length of your F&D cycles, because you have to tune the water flow into the GB to get the siphon operating and different diameter standpipes require different in-flow rates, so consequently they give different F&D cycle rates.