Spa water has a strong musty or moldy odor despite normal sanitizer levels

Safety: Wear gloves and eye protection when handling spa chemicals.

• Shock the spa: Add a high dose of chlorine or non-chlorine shock per Artesian’s water care guide and run all pumps with jets open.
• Use a plumbing purge product: Add a spa plumbing cleaner designed to remove biofilm, circulate per instructions, then drain the spa completely.
• Clean and replace filters: Deep clean filters with a filter cleaner or replace if more than 1–2 years old.
• Verify ozone/UV: Ensure the ozone generator or UV system (if equipped) is operating.

Refill with fresh water, balance chemistry, and maintain regular shock and filtration cycles to prevent recurrence.