We figured out that our pool is probably about 14 years old. We have to assume the liner is original. There are no leaks or tears. However, there is some severe discoloration on the bottom of the pool. In one corner it looks like a plume with no pattern (and it feels different on your feet) where we assume they poured in any chemicals which then made their way over to the bottom drain. The rest of the bottom is just really faded. The pattern should be the same as the walls and it is definitely not.
When should I think about replacing the liner? If it hold water, do I just leave it be? I don't want to spend money for just the cosmetic - the sparkling clear water more than makes up for that part.