I have a relatively new liner (installed professionally in 05). My pool is 13K gallons 14 x 28. About 4 weeks ago it developed a wrinkle in the shallow end about 2 feet long. Now I have a longer wrinkle on the ramp down to the deep end. CYA, alk and hardness are all very high from a bad algae problem last year - we left for a week and my filter shut off. I replaced 1/3 of the water at the start of the season. Does anyone know causes and how to correct?