I went to have my water tested for metals, because I noticed some rusty brown color on my boulders that I didn't have last year. He said I have some copper in the water. It came right off with the stain away stuff for metals that I usually use once a week. This timw though he said pour the whole bottle in, then backwash. What do u think it;s from, do u think the natural rocks give off copper? Iv'e read it could be from the winter algicide that the pool people put in? hope it's not a problem in the future, I wouldn't want the plaster to stain, for now it was only on the rock, but he says it was in the water as well. I do get alot of white scale on the tiles as well, even though I use the stain and scale remover weekly. Any help/ideas would be greatly appreciated, thanks, Michelle