Test strips are quick for spot checks but less precise. Liquid drop kits, especially those using an FAS-DPD titration for chlorine, give accurate free and combined chlorine readings and are what most experienced owners rely on. Digital photometers remove color guessing. Test free chlorine and pH several times a week, and alkalinity, calcium hardness and cyanuric acid less often.
You cannot balance what you do not measure. The test kit is the cheapest equipment upgrade with the biggest effect on water clarity and comfort.
Kit types
| Type | Accuracy | Speed | Best for |
|---|---|---|---|
| Test strips | Lower | Seconds | Quick checks, rentals |
| Color-match drop kits (OTO, phenol red) | Moderate | Minutes | Basic pH and chlorine |
| Titration drop kits (FAS-DPD) | High | Minutes | Owners who manage their own chemistry |
| Digital photometer | High | Minutes | Pros, colorblind owners |
| Salt meter or strips | Varies | Minutes | Salt pools |
What to test and target ranges
| Test | Typical target |
|---|---|
| Free chlorine | Depends on CYA; often 1 to 4 ppm minimum in pools without high CYA |
| Combined chlorine | Under 0.5 ppm |
| pH | 7.2 to 7.8 |
| Total alkalinity | About 60 to 120 ppm |
| Calcium hardness | About 200 to 400 ppm for plaster |
| Cyanuric acid (CYA) | About 30 to 50 ppm for chlorine pools, higher for salt |
| Salt | Per your cell, often about 3,000 to 3,500 ppm |
Follow your equipment and surface maker’s ranges where they differ, and your local health code for commercial pools.
Why chlorine depends on CYA
Stabilizer protects chlorine from sunlight but also slows it down. The higher your CYA, the more free chlorine you need to keep the same sanitizing power.
Salt pool owners should read our saltwater guide. Browse water chemistry.
Common questions
Are pool test strips accurate?
Good enough for quick checks, but less precise than drop kits, especially for chlorine at higher levels.
What is FAS-DPD?
A titration test that measures free and combined chlorine by counting drops until a color change, avoiding color matching.
How often should I test my pool?
Free chlorine and pH several times a week in season, and alkalinity, calcium and CYA every week or two.
What pH should a pool be?
About 7.2 to 7.8, with many owners aiming near 7.4 to 7.6.