Prevent algae growth with Phos-Out! Phosphates continually enter the pool water from a variety of sources, including liquid lawn fertilizers. Phosphates are terrific plant nutrients and, if left unchecked, will cause algae in your pool to grow and multiply. Use Phos-Out to reduce phosphates and you will use less chemicals. Phos-Out works with all types of sanitizers: chlorine, bromine, mineral systems, biguanides, and chlorine generators. Phos-Out is non-toxic and bidegradable, so it will leave your pool sparkling clean and algae-free.