Well I found a big part of it... in the return lines I drilled two very small holes just below the water line to be used as syphon breaks for when the power went out. Looks like I didn't drill the left side quite deep enough and the water coming out of those holes are right at the surface and that's causing some noise. I'll fill those holes in and drill a little deeper which should fix that.
I do still hear a bit of cavidation in the sump area still. I think it may be the right most valve which feeds the refugium. I think I may have the pipe that drops down into the refugium a bit too deep and it's not able to expell all of the air from the pipe. I'll try cutting that back a bit to see if that helps.
