Would love to hear advice and or experiences. While pulling a vacuum on the liner and filling the step seal kept coming loose, losing the vacuum on the liner. No wrinkles,in fact the opposite, very tight and lots of stretching in the wall vinyl. I stopped filling with water just up in the shallow end. I have about an 8 - 10 inch gap between the liner and wall. I'm afraid the liner is having to stretch too much and I'll have another seam failure. All measurements are right on. How much can a liner be expected to stretch.