NetSpa spa water feels slimy on the walls or has visible biofilm rings at the waterline.

Safety first: Do not use the spa until surfaces are cleaned and water is sanitized.

• Scrub surfaces: Use a soft spa-safe brush or cloth to scrub the walls and waterline of the NetSpa liner.
• Shock treatment: Apply a strong shock dose of sanitizer according to spa volume.
• Clean filter: Remove and thoroughly clean or replace the NetSpa filter cartridge.
• Consider line cleaner: Before the next drain/refill, use a spa plumbing line cleaner to remove internal biofilm.

Severe biofilm issues often require draining, deep cleaning, and refilling the spa.