We have a 28' above ground pool and had a new liner installed. The installers had us start filling with hose to 10", after that we had a water tanker for remainder. The overlap liner is sliding down on one side of pool. Stopped filling. Can this liner be stretched? I'm worried that this might happen again. Liner has 15 year warranty but install is 1 year. We have main drain and since cut has been add for drain and skimmer wii stretching ruin integrity of liner? Because they us fill with our well water my pool water looks like dirty green river water which is what didn't want and is why I opted to order water tankers. Apprx 5,500 gallons in pool now. Installer wants to fix and I think we should get a we liner. Looking for advice.