Flood and Drain speed?

[wh33t]

In my opinion, it doesn't matter much. The greatest benefit the flood/drain gives is the vacuum effect that forces highly oxygenated air into the lower grow bed area, which causes everything to thrive. So, as long as it floods and drains, you are fine!

Excellent reply man. Thank you for your advice. I presume as long as the roots stay wet the speed doesn't matter.

That's one aspect of it. You do NOT want to let the roots dry out. That is the fastest way to kill your plants! The other aspect is that if the plants are provided a constant flow of nutrients, even at low concentrations, they will still be readily available and allow the plant to stay healthy while cleaning the water for the fish. I have seen some home experiments that suggest that stopping the flow for short periods of time is more beneficial than constant flow or flood and drain, but I have yet to see such research in a published journal etc... and in fact have seen research published to the contrary, but not in direct contradiction to the fact... anyway too much info... yes, doesn't matter, just don't let it get dry!

Coming from a hydroponics background, that is the same advice I give to people as well. But I have also heard that there is some kind of aeroponic aspect to letting the roots get partially damp, as opposed to wet. It encourages their roots to turn fluffy white which apparently allows them to grab small micron sized droplets of water directly out of the air... or something like that.