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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