Hot tubs and spas
Small water changes fast. Get the doses right and the running costs under control.
A hot tub holds a few hundred gallons of 100 °F+ water shared by several people, so it needs more sanitizer per gallon than a pool and it changes faster. CDC recommends keeping free chlorine at 3 ppm or more in hot tubs, compared with 1 ppm in pools. Doses are small, which makes measuring accurately more important, not less.
Start with these tools
- Hot tub chemical calculatorEnter your hot tub's size and test results; get each chemical to add, in the right order, in grams and ounces.
- Hot tub electricity costEstimate what your hot tub adds to your electric bill each month, using its tested standby power and your local temperatures.
- Hot tub volume calculatorGet the maximum your hot tub could hold from its inside measurements, and how to find its true capacity for dosing.