New pool owner here, purchased a foreclosure in April 2014 and neighbors tell me at one point the pool was completely green/black. The majority of the staining is on the walls and a bit on the floors and looks as if when it was restored you can see the brush strokes on the surface where it was cleaned. I just tried the stain ID yesterday and based on testing it seems that these are copper stains. I applied some of the stop stain and hit with a wire brush which seemed to fade some of it out. Looking for feedback on this one. Thanks.