Chris,
I don't know if this would apply to your situation, I would run it by DaveJNZ via a private message. But, if you have an elbow in your overflow somewhere, you can drill a tiny hole on the top side of the elbow and it will allow that air to escape. I have it done on my system, and I was worried about water shooting out, but it doesn't at all, just spits out air. Good luck. Glad you got the skimmer working!