When should I use a phosphate remover for my pool?

Skip the phosphate remover unless you have a stubborn algae bloom that won’t die despite balanced pH, alkalinity, and adequate free chlorine. Phosphates are everywhere, but proper chlorine levels prevent algae from using them. Pool stores push phosphate removers as a recurring revenue stream, not a real necessity. If you do need one, use a lanthanum-based remover to bind and vacuum out phosphates, but fix your sanitation first.