Okay - busy with work so I could do yesterday was pull the cover and throw the robotic cleaner in (dolphin m4). The water level was to the brim so I put our cheap little pump in and pumped off the water to around the top of the skimmer. Unplugged the pump but left it in the water.
When I get up this morning, the water is about 2 inches below the skimmer! First though is if we had a leak, we wouldn't have had to pump water off. Second thought was maybe there was just some siphon action going on from the pump, which I removed.
Threw the hose in and turned it loose. Two hours later, it's come up a bit, okay - so far so good. 2 hours after that - it hasn't moved and it's still not even to the skimmer.
The plugs are all in still, so it can't be the plumbing. Could the robot have messed with the main drain? Or did it tear the liner somewhere? And what do I do? The water is dirty because a bunch of debris fell in it from the cover so I can't visually see anything.