zdoo2, I have found that adjustment takes a lot of patience. I would lower the bubbles in the intake & no bubbles would come up, so I'd raise it & it would overflow. I found if I had just waited a few hours with it lowered, it would have been fine. With that said, I wouldn't run it without the cup draining into another container (there's a plug in the bottom of the cup for that). Also, the pump should be as close to the skimmer as possible.