Pool Leak advice

[bluskyguy]

Hi Guys
Inground vinyl liner pool. Covered it back in October. Do not drain in winter (North Carolina),just run filter if
it goes below 32. Usually have to drain water via pool pump if we get alot of rain. Happened to notice in December
the level was a little lower than normal(via the skimmer). Long story short it seems to be holding at return level.Its
already in 70s here and I dont want to take cover off if I cant run filter. Talked to a Leslies pool guy who said
"American Leak Detectors" can come out and determine where leak is so I dont have to tear out ALL concrete
to find leak. Any info on these guys or other advice would be greatly appreciated. Thanks

 

[bluskyguy]

To add
Im assuming its a PVC plumbing leak due to it holding at return level,about a foot lower than normal.
I have been adding water every couple of weeks for the past two or so Summers thinking it was
evaporation, of course it never went a foot low but maybe it was a small leak that got bigger??