Hot Tub Chemical Calculator

Chemical doses for hot tub from volume and test results.

Tub Volume (gallons)

Current pH

Target pH

Current Alkalinity (ppm)

Target Alkalinity (ppm)

Current Free Chlorine (ppm)

Target Free Chlorine (ppm)

Tab to move between fields

pH Increaser / Soda Ash (oz)

9.6

pH Decreaser / Dry Acid (oz)

Chlorine Granules / Dichlor (oz)

2.4

Alkalinity Up / Baking Soda (oz)16

Total Chemicals (oz)28

Est. Monthly Chemical Cost ($)$12.64

Water per Change (gal)400

How to Use This Calculator

Test your hot tub water with a test strip or meter and note the current pH, alkalinity (ppm), and free chlorine (ppm).
Enter your hot tub volume in gallons (check owner's manual; typical 200-500 gal).
Input current and target values for pH (target 7.2-7.6), alkalinity (target 80-120 ppm), and free chlorine (target 3-5 ppm).
Review the calculated doses: pH increaser (soda ash) or decreaser (dry acid), alkalinity up (baking soda), and chlorine granules (dichlor) in ounces.
Add chemicals one at a time, circulate for 15 minutes, then retest before adding more.

Ad Placeholder