Why would a vinyl pool's liner color fade?

Sun and chlorine added over time. Also, there is a different type of chlorine/shock for vinyl liners. If your pool liner is still in good condition but have a faded tile border, buy BorderLines adhesive tile borders. BorderLines offers several nice tile patterns that just peel and stick to any smooth surface and can be done in a short afternoon by one person. I did it to mine and got a few extra years out of my pool liner before it needed replaced, Wow does my pool look new again, check it out at www.poolsandwaterfalls.com Good Luck