Hot Tub Calculator
Select your tub size and strip results to learn what to add and the proper order.
Ideal levels for hot tub water
For each test strip pad, the CDC and the AquaChek care guide provide these spa targets in ppm (parts per million).
- Chlorine in its free form
- 3–5 ppm
- Bromine (just for a bromine tub)
- 4–6 ppm
- pH target range (safe between 7.2 and 7.8)
- 7.4–7.6
- Alkalinity, the factor that keeps pH steady
- 80–120 ppm
If the water has a strange look or bad smell
Match what you see to a fix, with the correct dose for your tub included.
More hot tub calculator tools for heat and cost
Check this before buying or when your electric bill shows up.
Initial setup and regular maintenance
You will repeat these steps every few weeks or every few months.
How to read the strip the same way every time
Dip the strip, hold it flat, then match the pads to the bottle chart at the labeled time. View the pads in natural light rather than under blue tub lighting.
Start with alkalinity, then fix pH, and finally adjust the sanitizer. Each change influences the next, while the hot tub chemistry calculator shows the amount to add for each.