My salt water pool is 10 years old and the walls at the shallow end have suddenly developed 4 or 5 parallel horizontal wrinkles, about 12 inches long on the side walls and end wall, midway up from the floor (fibreglass stairs are located in the shallow end wall) These wrinkles have a "crunchy" feel (perhaps salt crystals?) There are also several smaller wrinkles near the inlet jets. The water has always been balanced using a Taylor K2006 test kit. The pool is in solid gravel with excellent drainage and fully surrounded/sealed by a large concrete deck. Possible excessive heat from the Coverstar cover has never been an issue in the past 6 years. Could the wrinkles be caused by a leak(s) in the liner? What action is required? Thanks very much!