Twice in the past week the air line outlet to the powerhead has gotten stopped up with algae or crud and allowed air to build up to the point the siphon stopped. The result was water on the floor. Needless to say, that ain't so good. It stops up on the inside at the opening to the fitting and can be easily cleaned with a toothpick. Anyone else had this problem? I'm about ready to get a conventional U tube overflow. I never have this problem with them.