Cloudy water almost always traces back to one of three things — chlorine, filtration, or balance. Here's how to tell which, and the exact dose to fix it for your gallons.
1. Low or ineffective chlorine. The most common cause. If free chlorine has dropped, or your stabilizer (CYA) is so high that chlorine can't work, water turns hazy and heads toward green. Test your free chlorine — if it's below about 3 ppm, raise it using the calculator above (it opens on the chlorine dose).
2. Filtration or circulation. A dirty filter, short run times, or poor circulation leaves fine particles suspended. Run the pump longer (many pools need 8–12 hours a day in season), backwash or clean the filter, and give it 24 hours before judging.
3. Chemical imbalance. High pH, high total alkalinity, or high calcium hardness can cloud water by causing scale to precipitate. Test pH and alkalinity; if pH is high, the calculator's Lower pH mode gives you the acid dose.
Test first, then work in order: get free chlorine into range, correct pH if it's above 7.8, run the filter continuously, and add a clarifier only if haze remains after chemistry is right. Retest before adding anything more — cloudiness often clears within 24–48 hours once chlorine and circulation are handled. If it's gone fully green, use the Green Pool Rescue flow instead.
It's best not to. Cloudy water can hide hazards and often signals low chlorine, which means bacteria and algae may be present. Clear the water and confirm chlorine is in range before swimming.
With chlorine corrected and the filter running continuously, mild cloudiness often clears in 24–48 hours. Heavier cases or those needing a clarifier can take a few days.
If the cause is low chlorine or early algae, raising chlorine (shocking) usually helps. If the cause is filtration or high pH, shocking alone won't fix it — address those too.