Hydroton or expanded clay pellets are really expensive, at least down here. I've decided to try hydroponics first and not add the fish to the mix. I'm going to use river gravel, it's heavy but it is cheap and doesn't raise the PH as the even cheaper limestone gravel would.
Pete, have you looked at Skippy type pond filters? I built one for a large pond in Calif and I grew tropical leafy plants, taro mostly, in the filter. They grew well in there and the system is very similar to a continuous flow hydro bed. I think that perhaps leafy vegetables like lettuce would do fine with minimal fish loads as you have. For fruiting things like tomatoes, you may need more nutrients. Just a thought.
I should start another thread with my hydro experiment.
