Frequency of flood and drain cycle?

[Patrick Roche]

I use a bell siphon on my outdoor aquaponic system and I'm wondering how often I should flood and drain the growbed. Is there a general rule of thumb?

With my pump, the bed fills up in about 12 minutes and then drains in about 3. I initially had the pump going continuously (24/7) but I was concerned that the plants might be getting too much water. Specifically, my peppers started getting some yellow leaves w/ small black spots.

In my indoor aquaponic system, I have the beds flood for 15 minutes every hour during the daylight and my peppers do great. So I decided to do the same for the outside system and I installed a 15 minute timer and now have it flooding just once per hour (about 15 minutes) during the daylight. Plants seem to be doing well, but there's a little yellowing still on some leaves that I'm concerned could spread if I don't get the flooding right.

So is this enough flooding? Too little? Should continous flooding and draining 24/7 work?

Some notes about my outdoor system, for what it's worth:

• I cycled tank using pure ammonia
• Nitrate is at about 80ppm
• Plants were started in established indoor aquaponic system then transplanted outside at seedling stage
• Fish were put in tank and plants transplanted about 2.5 weeks ago
• pH is between about 7.5-8
• Using expanded shale media

Thanks!

Patrick

[Sylvia Bernstein]

That's the aquaponics way, right Richard?  Always expanding...even if it means finding a new home to do so (just kidding... ) Good luck with the closing!