BioGuard Scale Inhibitor prevents scale build-up from high calcium levels. It also prevents stains caused by iron, copper and manganese. This product has recently been reformulated and is four times more effective than it was previously. Regular use of this new concentrated formula prevents scale build-up on pool surfaces, piping, filtration, and heating elements. This product will not affect pH. Scale Inhibitor will continue working 3-4 weeks after application.