I'm new, so sorry if this is old news. I am a Pristine Blue user. I have an issue with mineral staining on the floor of the deep of my vinyl lined in-ground pool. Last year I used the product above (sparkle conquest) with great results. This year, did the same thing and while it seemed to fade, now after a few weeks, its just as dark as before. My water balance is spot on so its frustrating that this keeps happening. I have another bottle of Sparkle Conquest but dont want to put it in if after a couple of weeks the stains return. I contacted Pristine Blue folks and they say Pristine is copper based so using sparkle is taking out the copper and using Pristine puts it right back in. I am on city water so I do not beleive its a metal issue from topping off. Any other Pristine Blue users experience this issue and how do you resolve it? thanks Coop