I opened my pool the middle of May and haven't gotten the liner clean yet. I thought maybe it was scaling because we have a private well and the water is very hard, but there are also black or very dark green spots, which I assumed was algae. The whole liner appears to have a white-ish coating on it and is rough. I read something about sand algae and thought maybe that was my problem, but I can't seem to find that post again. I have been told that I might can get it off if I keep my alkalinity low, but that could also cause damage to my heater, which I don't think I can bypass. I have been trying to keep the alkalinity in the 80-90 range and my chlorine as high as possible and have been brushing almost daily. At first I thought that was working because it seems like every time I brush I get a little more off, but here we are at the end of July and it is still there.
Also, we had pulled the ladder out of the pool and when it dried in the sun, I was very easily able to just brush it off. It did almost look like sand if you rubbed it off. I was able to pull away a couple of flakes with out them falling apart. I had read that if you put it in vinegar and it bubbled, that it was calcium. It did not bubble and it did not dissolve when left in a bowl of straight vinegar overnight. I don't know if that helps anyone figure out what it may be or not.
Here is my latest reading:
Cl - over 5.0 (it was darker than the yellow at 5.0)
Ph - 7.2
Alk - 80
Hardness - 460
CYA - 50
To add insult to injury, I must have a leak somewhere, as I have to add water weekly. I lose a good 4 - 5" at least weekly and as I said, it is well water that I am adding. This also makes it very hard to maintain consistent balance. Any ideas???