I'd just remove the cup and let the water over flow back into the tank. Get that aeration and return the bacteria back into the tank. The aeration is the most important part imo.
I also hooked my air inlet to a CO2 scrubber and have the skimmate flowing into an external container. I also connected the skimmate container to the inlet of the CO2 scrubber. Doing this keeps my pH between 8 and 8.2.
Yeah, I was going to go for the Curve 5, but I felt it would be a bit underpowered for a heavily stocked tank. Like Kasey said, shooting for double the tank volume is a good idea when running a heavily stocked tank.