Answer in brief

A quick reference to CDC hot-tub sanitizer and pH guidance, with reminders to follow your spa manual and chemical labels.

The key numbers

CDC guidance for hot tubs identifies at least 3 ppm free chlorine, or 4–8 ppm bromine, and pH 7.0–7.8. CDC's Legionella control toolkit gives an operating range of 3–10 ppm free chlorine or 4–8 ppm bromine with pH 7.2–7.8. Keep water temperature at or below 104°F (40°C). For your particular spa, use the current product label, manufacturer guidance, and any applicable local rules.

  • Free chlorine: CDC hot-tub guidance starts at 3 ppm; the toolkit lists 3–10 ppm.
  • Bromine: 4–8 ppm in CDC hot-tub guidance.
  • pH: 7.0–7.8 in CDC homeowner guidance; the toolkit's operating range is 7.2–7.8.
  • Temperature: no higher than 104°F (40°C).

Do not treat a chart as a dosing instruction

The amount of product to add depends on spa volume, current readings, sanitizer system, product concentration, and label directions. Measure first, add products separately, allow circulation, and retest. This page does not calculate doses.

A note on stabilized chlorine

CDC recommends not using cyanuric acid or chlorine products containing cyanuric acid in hot tubs because stabilization slows disinfection. Check the product label and spa-manufacturer instructions before choosing a sanitizer.

For a connected workbook and all five printable spa guides, see the complete Hot Tub Maintenance System on Etsy. The pages are educational tools; your manufacturer, product labels, and local requirements take priority.

Sources and further reading

Backyard Toolbox reviews practical guidance against current public-health, safety, and manufacturer information. Product-specific instructions always take priority.