Water has a strong chemical or musty odor despite normal sanitizer levels.

Safety first: Handle all chemicals with gloves and eye protection; follow label directions.

• Shock the spa: Add a non-chlorine or chlorine shock according to Hot Spring and chemical manufacturer guidelines.
• Clean or replace filters: Deep-clean filters or replace if more than 2–3 years old.
• Use a plumbing purge: Before the next drain, run a spa plumbing purge product to remove biofilm from lines, then drain and refill.