Pool Water Chemistry Basics: A Weekly Routine That Works
July 21, 2026 · 8 min read
Nearly every green pool traces back to one of three things: low sanitizer, drifting pH or stabilizer that crept too high. Test in a consistent order and you will catch all three before they become a weekend project.
The ranges to hold
Write these on the inside of your equipment shed door.
- Free chlorine: 2–4 ppm (or 7.5% of your CYA level)
- pH: 7.4–7.6
- Total alkalinity: 80–120 ppm
- Calcium hardness: 200–400 ppm
- Cyanuric acid: 30–50 ppm, 60–80 ppm for saltwater pools
Adjust in the right order
Alkalinity first, because it buffers pH. Then pH, then sanitizer. Adjusting chlorine before alkalinity means chasing the same numbers all week.
The ten-minute weekly routine
Test, brush walls, empty skimmer and pump baskets, check filter pressure against its clean baseline, then dose. Backwash or clean cartridges when pressure rises 8–10 psi over baseline — not on a calendar.
When to shock
Shock after heavy bather load, a storm, or when combined chloramines exceed 0.5 ppm. Do it at dusk so UV does not burn off the dose before it works.
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