micro bubbles.

[SuperFudge]

Steve,

If any pump is plumbed externally,it is probably getting air on the intake side of the pump...this was the case on a few that ive plumbed.(Teflon chincing ;) )

If it is in the sump,and no bubbles apparent where the pump sits,those anti siphons are the problem...(another that ive done).

I fixed them by placing the holes about 3/4" below water level,this way it will only siphon until water drops below this level,just make sure your sump can handle the extra capacity.. ;) .

Marc