Leaking Pool? Where is it coming from???

I'm asking this for my neighbor....

They have an aboveground pool with a sand filter...unsure of size but if needed I'll get it from them. They have an automatic pool cleaner - Polaris 65 - From what they say it seems whenever the Polaris is running they lose water...about 2" per day. They thought they had a leak in the liner so they searched for holes and nothing...they can't figure out why/where it is leaking. They didn't use the Polaris for a few days and noticed it wasn't leaking but now they have put the Polaris back in - its leaking again...

Any ideas????? I don't see why the Polaris would make a difference seeing that it plugs directly into the skimmer, it doesn't make sense to me.....

Any help would be greatly appreciated!!

Thanks!

The only thing I can think of is that the polaris is making the skimmer shake, this in turn could be opening up a hairline crack somewhere in the skimmer thus they lose a noticeable amount of water. Maybe the crack somewhat reseals itself without the shaking of the polaris....

I'll ask them - thanks a bunch!

They are so frustrated because they can't find the leak anywhere - hopefully this will help!

Thanks again!! :)