Hot Tub Volume & Drain Schedule
Estimate your hot tub's gallons by seat count, and find out how often to drain and refill based on daily use.
Estimated volume
Enter your numbers above to see the result.
Suggested drain & refill interval
Enter your numbers above to see the result.
Safety first
- Never mix chemicals together.
- Always add the chemical to the water — never water to the chemical.
- Wear gloves and eye protection when handling pool/spa chemicals.
- Keep chemicals out of reach of children and pets.
- Always follow the product label — it overrides any guidance here.
Frequently asked questions
I don't know my hot tub's exact gallons — what do I do?
Check your owner's manual first — it's usually printed there. If you can't find it, use the seat-count estimate below; it's rough but good enough for most chemical dosing.
How often should I drain and refill my hot tub?
Every 3-4 months for typical use, sooner with heavy use or if foam/odor builds up despite regular chemicals.
Why does drain frequency depend on how many people use it?
More bathers means more body oils, lotions, and waste building up in the water, which your sanitizer and filter have to work harder to handle — so the water needs replacing more often.
How often should I clean the filter?
Every 2-4 weeks, more often with heavy use.