Quote Originally Posted by matt4x4
Also, if your water level is pretty low (just above skimmer) it's even easier for air to get sucked in around the adapter, always make sure your adapter seals well, even though it sits in there good, sometimes you get more leakage than other times
I have a vacuum problem that's a variation on this. I should probably replace the vacuum hose, but it can leak air at the end that connects to the vacuum adapter or plate that goes into the skimmer. When the hose moves around, a leak can open up between the hose and the hose end/connector, which is above the water line. My cheapo solution is to run water from a garden hose over this joint while I'm vacuuming. This keeps air from getting into the system and wrecking the vacuum.

Rick