[Troy F]

Patrick, the PH you are using should be able to run full out without bubbles. I had 8 different pumps (7 powerheads and a little giant on closed loop) and never had bubbles. One of the things that can cause the bubbles is having the pump close to the surface where its jet can grab air. You're not using a venturi feature with your pumps are you?

Without overflows it is tough to avoid a surface film, some people just point a powerhead at the surface.