Pool and spa chemistry levels
What each reading should be
- Free chlorine
- 1–10 ppm Florida 64E-9.004
- pH
- 7.2–7.8 pH COMAR 10.17.01.45
- Total alkalinity
- 60–180 ppm COMAR 10.17.01.45
- Calcium hardness
- 150–400 ppm COMAR 10.17.01.45
- Stabilizer
- up to 100 ppm Florida 64E-9.004
Every band, and who sets it
A pool
| Reading | Range | Ideal |
|---|---|---|
| Free chlorine Florida 64E-9.004 (1)(d)2 |
1–10 ppm | 2–4 |
| pH COMAR 10.17.01.45 A(1) |
7.2–7.8 pH | 7.4–7.6 |
| pH Florida 64E-9.004 (1)(d)1 |
7.0–7.8 pH | none stated |
| Total alkalinity COMAR 10.17.01.45 A(2) |
60–180 ppm | 80–120 |
| Calcium hardness COMAR 10.17.01.45 A(3) |
150–400 ppm | 200–400 |
| Stabilizer Florida 64E-9.004 (1)(d)4 |
up to 100 ppm | 30–50 |
| Saturation index COMAR 10.17.01.45 |
−0.5 to +0.5 index | none stated |
A stabilised pool
| Reading | Range | Ideal |
|---|---|---|
| Free chlorine CDC Healthy Swimming |
2 and up ppm | none stated |
An indoor pool
| Reading | Range | Ideal |
|---|---|---|
| Free chlorine Florida 64E-9.004 (1)(d)2 |
up to 5 ppm | none stated |
A salt water pool
| Reading | Range | Ideal |
|---|---|---|
| Dissolved solids COMAR 10.17.01.45 A(5) |
up to 3,000 ppm | none stated |
A spa or hot tub
| Reading | Range | Ideal |
|---|---|---|
| pH COMAR 10.17.01.45 A(1) |
7.2–7.8 pH | none stated |
| Free chlorine Florida 64E-9.004 (1)(d)2 |
2–5 ppm | none stated |
| Total alkalinity COMAR 10.17.01.45 A(2) |
60–180 ppm | none stated |
| Calcium hardness COMAR 10.17.01.45 A(3) |
150–400 ppm | none stated |
| Stabilizer Florida 64E-9.004 (1)(d)4 |
up to 40 ppm | none stated |
| Water temperature COMAR 10.17.01.45 C(2) |
up to 104 °F | none stated |
Pool and spa rules are adopted and amended state by state, and most of the ranges here are written for public pools. Confirm every figure against the code your jurisdiction has adopted and against your own product label.
Fix a reading
Updated October 2026
Sources and dates
Ranges are quoted from the code named beside them, product strengths from the manufacturer's own product page, each retrieved on the date shown.
- Florida 64E-9.004 (1)(d)2 · http://flrules.elaws.us/fac/64e-9.004 · 2026-09-17
- HASA · https://hasa.com/pool-chemical-calculator · 2026-09-17
- COMAR 10.17.01.45 A(1) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- Florida 64E-9.004 (1)(d)1 · http://flrules.elaws.us/fac/64e-9.004 · 2026-09-17
- COMAR 10.17.01.45 A(2) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- COMAR 10.17.01.45 A(3) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- Florida 64E-9.004 (1)(d)4 · http://flrules.elaws.us/fac/64e-9.004 · 2026-09-17
- CDC Healthy Swimming · https://www.cdc.gov/healthy-swimming/about/home-pool-and-hot-tub-water-treatment-and-testing.html · 2026-09-17
- COMAR 10.17.01.45 · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- COMAR 10.17.01.45 C(2) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17
- COMAR 10.17.01.45 A(5) · https://www.law.cornell.edu/regulations/maryland/COMAR-10-17-01-45 · 2026-09-17