Ron, you said recently on the bulletin board that you were waiting for someone to construct an inexpensive cycle timer. I think the question asked was if it was okay to leave the plant roots in the solution for 15 min at a time. ie, 15 min
pump on, 15 min pump off. I have constructed a cycle timer that will turn on the pump every 15 min for any duration required. So you could have it set to come on at 15 min intervals but only run for 5 min. Drop me a line if you are interested.
thesteeds@telus.net