What causes foamy pool water and how do I fix it?

Foamy pool water is caused by chemical imbalance — usually too much algaecide, high calcium hardness above 400 ppm, or a phosphate overload from leaves or fertilizers. Fix it by testing your water first, then shocking the pool to break down organic residue. If that doesn’t work, check calcium and phosphate levels and adjust. A pool defoamer knocks foam down quickly, but it’s a bandaid — balanced water chemistry is the real solution.