About 3 years ago, we started getting wrinkles in the bottom of our vinyl liner, first started in shallow end and now are in the deep end. We have concrete under our vinyl and our vinyl liner is about 10 years old--it still looks great except for the wrinkles. I use borax, baking soda, and the tri-clor tablets for maintenance. I don't believe I have a leak as the water level doesn't change much. I have always struggled keeping my ph up and go through a lot of borax. Last year I really tried to notice when a new wrinkle appeared. I keep a solar blanket on the majority of the time when not in use as I like 84 plus degree water and sometimes our pool temp gets 86 to 88 during July--I usually can go a couple of weeks in July without the solar cover. It seemed that wrinkles would appear when the solar cover was on. Could my ph be causing the problem?
20 x 40 vinyl liner, concrete underneath, IG, sand filter 30,000 gal