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Step-by-step plan

Green pool? A step-by-step plan to clear it

Green water usually means algae is growing faster than your sanitizer can kill it. Most green pools clear with steady chlorine, good filtration and patience. Here is the order to follow. Small pools with mild algae can clear in a few days; heavy algae or high stabilizer takes longer.

Updated October 4, 2026

The 5-step chemistry checklist

  1. Get the filter and pump running right. Empty baskets, clean or backwash the filter, and run the pump continuously until the water is clear. Algae you kill has to be filtered out.
  2. Test before you add anything. Test free chlorine, pH, total alkalinity and stabilizer (CYA). A drop kit is more reliable than strips for this job. Write the numbers down.
  3. Bring pH into range first. Chlorine works much better when pH is in the range your test kit lists (commonly about 7.2 to 7.8). Adjust in small, measured doses and retest after circulating.
  4. Raise chlorine and hold it. Add chlorine per the label to a level high enough for your stabilizer reading, then keep it there. Retest several times a day and top up as it drops. Brush walls and floor each day to break up algae.
  5. Keep going until it passes all three checks. Water is clear enough to see the main drain, chlorine holds overnight with little loss, and the filter pressure is back near baseline after a final clean.

Why it might not clear

  • Chlorine level too low for the stabilizer level, so it never catches up.
  • Pump not running long enough, or the filter is dirty or damaged.
  • Dead spots behind ladders, steps and lights that are not being brushed.
  • Very high stabilizer. The usual fix is partial water replacement; ask a pool professional.

Tools for this job

A liquid drop test kit (for example a Taylor kit), test strips for quick between-checks (for example AquaChek), a brush, and fresh chlorine. See test kits compared and the gear list.

Taylor K-2006-SALT saltwater pool test kit

Liquid drop kit (Taylor Technologies K-2006-SALT, FAS-DPD). Covers the chlorine, pH and alkalinity checks in guide 4 and the green-pool plan, plus salt, hardness and stabilizer.

AquaChek Yellow 4-Way test strips (50 strips)

Smaller bottle of strips for the basics: free chlorine, pH, total alkalinity and stabilizer (cyanuric acid).

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