Winter Leak

[poolman10]

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?

Thank you.

Edit: forgot to add that the pool was professionally closed with plugs in the return and skimmer.

 

[poolman10]

I posted the question above back in March when things were a little quiet, so bumping now that pool openings are in full swing. The water is still just above the return despite the rains we've had. I've looked along the waterline but don't see any cracks in the liner though will look again if the rain ever stops. Do anyone ever see leaks below a waterline that's settled at a certain level?
Thanks.

 

[poolman10]

Am still working on this problem and just had a thought that I'd like to run by the smart people here.

When I closed the pool in the fall, I dropped the water level by means of a siphon. I put one end of a garden hose several inches down in the water and ran the other end out into the woods behind the pool. The woods end of the hose was several feet below the water level of the pool. Created a siphon and the water ran out of the pool until the water level reached the bottom of the hose.

As I said in my earlier post, we had rains in the fall to the point that the water level reached just above the bottom of the skimmer. We then had a deep freeze in December/January, and when I checked the water level in March, after the thaw, it was down to several inches below the skimmer. It just dawned on me that it may have dropped to the level of the end of the hose that I used for the siphon in the fall, though I pulled the hose a few weeks ago, so I don't know for sure.

With our spring rains, the water level is back up a couple of inches. Have searched in vain for tears in the vinyl at the water level but haven't found anything. Is it possible that the siphon restarted itself after the ice thawed??

Thanks.