Phosfree by Natural Chemistry is a phosphate remover for spas and hot tubs. Phosphates are compounds that can enter the water from various sources, including detergents, fertilizers, and organic waste. High phosphate levels in the water can lead to water quality issues, algae growth, and reduced sanitizer effectiveness. Phosfree works to eliminate phosphates, helping to maintain balanced water chemistry and prevent problems associated with phosphate buildup.