Hot Tubs & Spas

5 free calculators — every one shows its formula and a worked example.

Hot Tub Chemical CalculatorEvery spa reading graded at once, with teaspoon doses and a drain date.Hot Tub Volume CalculatorYour spa's real gallons — seats lie, tape measures don't.Hot Tub Shock CalculatorSpa shock doses by the gram, chlorine or non-chlorine.Hot Tub Bromine CalculatorBromine granule doses in teaspoons, plus the fresh-fill startup routine.Hot Tub Chlorine CalculatorSpa-sized chlorine doses in teaspoons — small water, exact math.

Pool care reminders, right on time

A short email when it matters: opening season, heat waves that eat chlorine, closing time. No spam, ever.