I am in CT and have a 20x40 vinyl liner pool with one skimmer and one return. A couple of months ago, just before a big freeze, I checked the water level and it was just at the bottom of the skimmer opening. Since then, the temperatures dropped to the teens for several days and we had 15 inches of snow, and then a total thaw.
I checked the water level again two days ago and it is now 6 inches below what it was before the freeze. It is well below the skimmer, but two inches above the return. There is no obvious place (e.g. light, return, rip, etc.) where the water can escape from. Any thoughts?
Edit: forgot to add that the pool was professionally closed with plugs in the return and skimmer.