I had a lot of stains on my pool. I had used some Clorox Xtra Blue tabs with copper in them and it stained my pool bad. I had these dark stains all over my pool. I wasn't sure this product would work because I had tried other stain removes and the stains would come right back. I tried this out and it worked. The stains came off right away and then the liquid must have worked with the Culator because my stains didn't come back all summer. And, I stopped using clorox tabs. I recommend the stain kit.