Helping son close his pool which is inground vinyl liner for first time. Pool is Salt System , 27000 gals, DE filter with a heater . Readings PH 7.5 FC 6.0 CC 0.0 Akl- 90 Calcium Hardness 170 CYA 50 Water is clear . Took water down as in process of closing and noticed from water line down the liner has a faded look to it or like a white film . For sure on the dark tile of the top of the liner and appears to go all the way down on the pebble portion . Took a magic eraser and scrub and it lighten some but not a lot . Some dirt on the magic eraser after scrubbing . Cant imagine its fading as liner is only 2 ful years as put in late fall 2017 . Pool company has always closed so we are doing it ourselves as I have had pool since 1989 so helping . Any suggestion on liner would help