Hot Tub Water Foaming Excessively — San Francisco, California

Thick foam building up on the surface of your hot tub when the jets are running is usually caused by a buildup of body oils, lotions, detergent residues from swimsuits, or dissolved organic compounds that the sanitizer can no longer break down. Low sanitizer levels, an imbalanced pH, or an old and saturated filter all accelerate the problem. While anti-foam chemicals offer a temporary fix, persistent foaming typically means the water chemistry needs a complete reset — draining, cleaning the shell and plumbing lines, replacing the filter cartridge, and refilling with properly balanced fresh water. A pool and spa technician can test the water, flush the internal plumbing with a line purge product, and set up a maintenance schedule that prevents the foam from returning.