Pat:
Liners fade. There's nothing you can do about that. UV rays will simply fade all liners, regardless of chlorine. Chlorine levels at 15ppm with no CYA will fade them faster, that's all.

I can see how my liner faded in two years from the drop-in steps. That spot is darker than the rest. Good thing the steps will go back there again!

Would you rather slow down your fading by keeping chlorine below 3ppm or not have an algae bloom? That's really the choice. Truly, you are better off concentrating on keeping the water sanitary.

BTW, that 3ppm is nonsense--the pool liner company cites it because the EPA says that's the max swimming water should be for safety. Recommending higher levels than that may introduce a legal liability so that's all they'll say. Curiously, the same agency (EPA) says DRINKING water can be 4ppm, and even, under certain conditions, as high as 10ppm. So somehow, magically, it's safe to drink water that it's not safe to swim in....