I've got a DIY scrubber that is similar to an SM100, except that I stretched it to 10" tall to fit 6 T5HO bulbs instead of 4. It is working fine except that my drains are sucking air and are gurgling noisily. I've got two 3/4" bulkheads for drains. They suck air when full open with a 1" hole and when restricted to a 3/4" hole. There is around 1-1.5" of water in the chamber when running. I can tune the water level by opening or closing the flow (both the inflow and the drain flow), but I've been unable to stop the gurgling unless I just about fill the chamber with water. Are there any tricks to keeping the drains from sucking air? Would anything change if I go to a single, larger bulkhead?