Green Pool Water: How to Clear It
Green pool water is almost always algae from low chlorine — sometimes metals. Here's how to tell them apart and clear a green pool.
Updated June 2026
Quick answer
Green water is almost always algae, caused by chlorine dropping too low. The fix: balance pH, shock hard, brush the walls and floor, and run the filter around the clock until it clears. If the water turned green after you added chlorine (and clears as you do), the cause is metals instead — that needs a sequestrant, not more shock.
Algae or metals? Tell them apart first
- Algae (most common) — water went green over days as chlorine fell; it looks cloudy-green and walls feel slick. Adding chlorine helps.
- Metals (less common) — water turned green/clear right after adding chlorine or fresh fill water; it's often clear, not slimy. Copper or iron is reacting. More chlorine makes staining worse, not better — you need a metal sequestrant.
How to clear a green (algae) pool
- 1
Balance pH
Bring pH to the low end of range (around 7.2) so the shock works at full strength.
- 2
Shock hard
Algae needs a heavy chlorine dose — well above a routine shock. Do it at dusk so the sun doesn't burn it off.
- 3
Brush every surface
Brush walls, floor, and corners to break up algae so the chlorine and filter can reach it.
- 4
Run the filter nonstop
Circulate 24/7, cleaning or backwashing as it loads up with dead algae.
- 5
Add algaecide if needed
Once chlorine has done the heavy lifting, an algaecide helps finish and prevent a comeback.
- 6
Hold chlorine and re-test
Keep free chlorine elevated until the water clears, then return it to 1–3 ppm.
Aquavail sizes the shock to your pool and walks the order — balance, shock, filter — so a green pool comes back without guesswork.
Common questions
How long does it take to clear a green pool?
A mild green often clears in a day or two with a strong shock, brushing, and continuous filtration. A deep, dark-green pool can take several days and repeated shocking. Keeping free chlorine elevated and the filter running is what gets it done.
Why did my pool turn green after I shocked it?
That points to metals (usually copper or iron), not algae — the chlorine oxidized dissolved metal and tinted the water. Don't keep shocking; add a metal sequestrant, which binds the metal so the filter can handle it and staining is avoided.
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