Yesterday when I opened the auto cover on our pool I seen a big wrinkle about 18" long below the simmer. It ran from the simmer on the wall towards the bottom of the pool. Sorry I didn't get a pic of it. I was able to work the wrinkle out and can't tell it was even there now. Here are my numbers.
I am having a FC drop of 2.5 to 3.0 a day. Was adding CL to 9 to account for that. Was running variable speed pump 16 hours a day. Not running from 12:00 AM to 8:00 AM. CL PH Testing and adding CL at 8:00 PM. Closing cover after that to keep heat in water. Run heater from 8:00 am to 12:00 pm if needed. I heat the water to 82 degrees.
I don't think that it was a chemical wrinkle as I was able to get it out of the liner.
Last night I left the pump run on 1200 rpm all night and no wrinkle today not saying that was what caused it.
Have used the auto cover closed with heat on before during the last three years.
We have had no large rain amounts and there was no water behind the liner.
I really don't know what caused the wrinkle so I would like your opinion.