Cal-Hypo and Black Pool Stains: Bob Lowry Explains

A black stain appears the moment cal hypo hits the floor—panic sets in. We unpack why that stain isn’t a new disaster but copper changing form, and how to turn a scary moment into a clean, controlled fix. With guidance from Bob Lowry, we break down the chemistry that matters, the tools that actually remove metals, and the habits that keep stains from returning. We start with the copper story: how copper sulfate hides in plain sight until oxidation turns it into black copper oxide, and why as...