Hot tub dose calculator
Enter your tub size and what your test kit reads. You get how much baking soda and dichlor to add, whether to shock, and when the next drain is due, in the order to do it.
Work out tonight's doses
Type in your tub's gallons and what your test kit reads. The steps come out in the order to do them: alkalinity, then pH, then chlorine.
Doses assume dichlor at 56% available chlorine and plain baking soda. Check your product label, add half, run the jets 20-30 minutes, and retest before adding the rest. Not sure of your gallons? Find your real number.
What to do, in order
Enter at least one reading to see your steps.
How the numbers are worked out: dichlor at 56% available chlorine raises free chlorine about 1 ppm per 0.024 oz for every 100 gallons; baking soda raises alkalinity about 10 ppm per 0.24 oz for every 100 gallons; dichlor adds roughly 0.9 ppm of cyanuric acid for every 1 ppm of chlorine; combined chlorine above 0.5 ppm is the cue to shock; days between drains are gallons divided by 3, divided by daily users. The full reasoning is in hot tub water chemistry in plain words.