Hot tubs
Spa water is the hardest case in water care: a little hot water, a lot of people. Here is everything to keep it clean, plus help buying one.
- Calculator
Hot Tub Volume Calculator
How many gallons your spa holds, the number every dose depends on.
- Calculator
Hot Tub Chemical Calculator
Chlorine, bromine, and shock doses for your spa volume.
- Guide
Hot Tub Maintenance
The short, repeatable routine that keeps spa water clear.
- Guide
Why Is My Hot Tub Foaming?
What causes spa foam and how to fix it for good.
- Compare
Bromine vs Chlorine
Which sanitizer to run in a hot tub, and why bromine suits hot water.
- Review
Best Inflatable Hot Tubs
Picks by category plus what to check before you buy.
Spa chemistry is dosed per gallon just like a pool, so the pool calculators work for a hot tub once you know its volume. More hot tub guides are added regularly.