Actually, when the air intake cloggs the water level drops cuz their is no air mixed with the water. So I think this is the problem with op.Usually when this happens the skimmer overflows the collection cup with saltwater. Being that OP is getting little to no bubbles and no overflow I don't think this is the case, but its still good to check
that doesn't make any sense.....if the pump is allowed to pump water only, without the injection of air, it basically becomes a return pump and is going to pump pure water, causing the skimmer to overflow. The injection of the air is what lowers the water level as the flow into the skimmer chamber is interrupted by the addition of air. Think of your return pump pumping water into your display, if you suddenly hooked an airhose up to it and injected air into the line with your return water, you're going to get less water and tons of microbubbles and air bubbles as pushing air has less resistance than pushing water. So if you plug the air line going into your return, the result is constant flowing water.
I guess it depends on the design of the skimmer. With my reef octopus, if you completely block the air intake, the water raises up and overflows into the skimmer cup.
What kind of skimmer? Any needle wheel skimmer I've owned overflowed when the airline clogged so cleaning it was part of my maintenance routine. I'm sure different skimmer designs produce different results so dont take this as argumentative.
