I am losing ~1.5" per day out of my vinyl lined inground pool. It's ~28K gallons, liner is new as of two years ago.

I've heard that one can use food coloring/dye to detect leaks by squirting it around suspected leak points to see if it gets sucked in, and I have tried this without success. There were a number of holes last year around the steps that were patched, I tried this area and did not see anything amiss. Ditto for the return jets, skimmer, and main drain (I got as close as I could, ~3ft away -- but not sure how close the dye has to be to see the effect).

Two odd things about this pool...

1) Last year we had this same issue... losing tons of water later in the season although it was fine at the beginning of the year.

2) Last year and again this year we had major issues with the not being able to purge all the air out of the skimmer basket early in the year, but things seemed to work themselves out after a couple weeks.

For the latter issue we had the local pool place come out and do leak testing of the skimmer line and they did not see a problem, we skipped testing the main drain because they said we would have to pay for a diver to plug the bottom of the pool.

Possible that these two issues are related? I'm focused on the leak right now and hoping for help on that, but maybe there's a bigger picture that I'm missing?