Spa Calc

Is my hot tub ready to use? Soak, wait or fix first

Soak when free chlorine is 3 to 5 ppm (bromine 4 to 6), pH is 7.2 to 7.8, and at least 15 minutes have passed since you added anything (20 after pH decreaser). Above 5 ppm chlorine or 6 ppm bromine, wait. Above 10 ppm chlorine, 8 ppm bromine, or with pH below 7.0 or above 7.8, it is not safe.

Ready to soak?

ppm
ppm
min

Wait 5 min

Give it at least 15 minutes with the jets running and the cover open, then retest.

  • Soak range for free chlorine: 3 ppm to 5 ppm (and at least 7.5% of your CYA), with pH 7.2 to 7.8. Below pH 7.0 or above 7.8 it is not safe. Hot tub limits based on CDC guidance and EPA product labels; your product label comes first.

Save this test and get a reminder before your next soak.

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How the answer is decided

  1. Not safe: free chlorine above 10 ppm, bromine above 8 ppm, or pH below 7.0 or above 7.8 (CDC).
  2. Then the wait after a dose: at least 15 minutes after most chemicals and 20 after acid, jets running and cover open. After chlorine, bromine or a shock in a bromine tub, test again before soaking.
  3. Wait, levels still high: free chlorine above 5 ppm (many chlorine labels say not to get in above 5 ppm) or bromine above 6 ppm.
  4. Fix first: add sanitizer when free chlorine is below 3 ppm (or below 7.5% of your CYA, if higher) or bromine below 4 ppm; raise pH when it is 7.0 to 7.2; drain and refill when CYA is so high that chlorine would need to be above 5 ppm.
  5. Ready to soak: everything above is clear, with pH 7.2 to 7.8. These hot tub limits are based on CDC guidance and EPA product labels; your product label comes first.

Questions

How long after shock can I use the hot tub?

After non-chlorine shock, many labels allow about 15 minutes; in a bromine tub, test bromine first, because the shock turns bromide into bromine. After chlorine shock, wait until free chlorine is back to 5 ppm or less, and never get in above 10 ppm.

Is it safe to soak with no chlorine?

No. Without sanitizer, bacteria that cause hot tub rash can grow quickly in warm water.

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