I have no knowledge of the air systems whatsoever. But it almost sounds like a vacuum leak. Like maybe not a good connection or a split in the line somewhere. Like I said I have zero knowledge on this just a thought in my head.

The people who say I can't do it can just sit the @^#% down and watch me. Friends call me Rusto I also subscribe to pond boss mag. http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=504716#Post504716