Revamped the setup a few months ago. Will post pics as soon as I can find camera. Seems to have disappeared after last trip to Hawaii.
Moved the fish tank to an elevated table and am using gravity flow to irrigate beds. Bell siphon has been running for a year without a hitch! (Hoo Yah). Cut a 55 gal barrel in half and am using it for the sump tank. Pump sits in it and pumps directly into fish tank. Changed the airpump to a much higher output system.
Benefits: Fish are no longer under grow beds where I have to contort myself to see and feed. Pump outlet is on bottom of fish tank and keeps the excrement in motion constantly. (With the help of the airstones). Tank is much cleaner, fish are quite a bit more active and healthy, more nutrients are going to the beds on an ongoing basis. Water quality has been excellent.
Dumb moves: washed the entire batch of hydroton when I changed setup. Pretty much set back the bacteria load months. Oh well...
Wish I had better answers on: chelated iron. Found it in my local farm store but still hesitant to use in setup as I was told that if it has zinc it will kill the fish. Hard to get information online, having to call company. Bought the EDDHA variety (6%) but it was sold as a soil amendment. Anyone have an opinion?