Ideal Pool Chemistry Levels Chart
Pick your pool type for exact targets. Print it and keep it by the test kit.
Updated · Reviewed by the Skimmer editorial team
| Reading | Min | Max | Target | Too low: add | Too high: do |
|---|---|---|---|---|---|
| Free chlorine | 3 | 7 | From your CYA (chart below) | Liquid chlorine or cal-hypo | Stop dosing, wait |
| pH | 7.2 | 7.8 | 7.6 | Soda ash | Muriatic or dry acid |
| Total alkalinity | 60 | 120 | 90 | Baking soda | Acid, then aerate |
| Calcium hardness | 250 | 400 | 330 | Calcium chloride | Partial drain and refill |
| Cyanuric acid | 30 | 50 | 40 | Stabilizer | Partial drain and refill |
| Combined chlorine | 0 | 0.5 | 0 | Nothing | Shock to breakpoint |
| CSI / LSI | -0.3 | +0.3 | 0 | Raise pH, TA or CH | Lower pH or TA |
| Phosphates (optional) | 0 | 1,000 ppb | Under 500 ppb | Nothing | Optional remover; keep FC up first |
| Borates (optional) | 30 | 50 | 50 if used | Borax plus acid | Drain and refill |
Min and max follow the CDC and ANSI/APSP-11 industry ranges. The target column is the tighter number most experienced owners aim for. Plaster, gunite and pebble need calcium to avoid etching. Trichlor tabs add CYA and lower pH and TA over the season, so trichlor pools need CYA checked more often.
Free chlorine by CYA
The more stabilizer in the water, the more free chlorine you need. Enter your CYA below to highlight your row.
| CYA (ppm) | Minimum FC | Target FC | SLAM / shock FC |
|---|---|---|---|
| 20 | 1.5 | 2.5 | 10 |
| 30 | 2.5 | 3.5 | 12 |
| 40 | 3 | 4.5 | 16 |
| 50 | 4 | 6 | 20 |
| 60 | 4.5 | 7 | 24 |
| 70 | 5.5 | 8 | 28 |
| 80 | 6 | 9 | 32 |
| 90 | 7 | 10.5 | 36 |
Minimum is about 7.5% of CYA (liquid or tabs), SLAM is about 40%. Dose with the pool chlorine calculator.
Enter today's readings
Type in today's test results. Leave any blank.
Industry range vs the number to aim for
Most charts print the CDC and ANSI/APSP-11 ranges: total alkalinity 60 to 120 ppm and calcium hardness 200 to 400 ppm. Those are safe limits, not targets. Owners who keep the tightest water usually aim lower on alkalinity (around 70 to 90 ppm) because pH drifts up more slowly, and they set calcium by surface: plaster needs it, vinyl and fiberglass do not.
Free chlorine is the one number a fixed chart gets wrong. Cyanuric acid (stabilizer) protects chlorine from sunlight but also slows it down, so the right free chlorine rises with CYA. That is why the chart above lists FC by CYA instead of a flat 1 to 3 ppm.
How often to test each reading
| Reading | Test how often |
|---|---|
| Free chlorine and pH | 2 to 3 times a week (daily in a heat wave) |
| Total alkalinity | Weekly |
| Combined chlorine | Weekly, and after heavy use |
| Calcium hardness, CYA, salt | Monthly |
| Phosphates, borates | Only if you use or chase them |
Sources
Figures and safety guidance on this page draw on the following public references.
- 1.U.S. Centers for Disease Control and Prevention. Model Aquatic Health Code (MAHC)
- 2.U.S. Centers for Disease Control and Prevention. Healthy Swimming: Pool Chemistry & Disinfection
- 3.The Pool & Hot Tub Alliance (ANSI/APSP/ICC-11). American National Standard for Water Quality in Public Pools & Spas
- 4.American Water Works Association. Langelier Saturation Index (water balance reference)
Free from skimmerpoolcare.com. Log today's test in Skimmer: Pool Care Log on the App Store.
General reference for residential pools. Product labels and local guidance override any figure here. See our methodology and editorial policy. Skimmer · skimmer pool care.