How do I fix my black pool water?
Water color resulting from oxidized metals can come in an assortment of colors, and is mostly translucent in its early stages. Green, red, brown, and black are some of the more common colors produced by dissolved metals. Green color is usually produced by either copper or iron. Red and brown colors are generated by iron. Black/brown pool water is usually caused by manganese.
Often these colored water conditions appear after a pool is initially filled or after a Shock Treatment. If the fill water contains metals it should be treated with a sequestering agent and/or clarifier prior to chlorine additions. A shock treatment can cause metals to oxidize, which allows them to fall out of solution and become more visually apparent.