Why your pool won’t hold chlorine
If chlorine disappears, you usually have one of three problems: no stabilizer (CYA), so sunlight burns it off; an algae or organic demand eating it; or high combined chlorine. Stabilize and shock as needed.
Step by step
- Check CYA (stabilizer)With little or no CYA, sunlight destroys chlorine within hours. Bring CYA to 30–50 (60–80 for salt pools).
- Check combined chlorineIf total chlorine is more than 0.5 above free chlorine, organics are using it up — shock the pool.
- Look for a hidden algae demandIf chlorine vanishes overnight, treat it like an early bloom and shock until it holds.
FAQ
How much CYA should I have?
30–50 ppm for a chlorine pool, 60–80 ppm for saltwater. Use the CYA calculator for the exact stabilizer amount.
Related
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