Troubleshooting guide
Green pool water
Green water means algae got ahead of your sanitizer. Clearing it is mostly chemistry and filtering, but the real question is why the chlorine ran out.
Why the chlorine ran out
- The pump or chlorinator stopped. A tripped breaker, a timer issue or a pump that lost prime means no filtering and, on a salt pool, no chlorine.
- Salt system not producing. Hayward's AquaRite stops generating on no flow, very low salt, high salt or a dirty cell, and below 50°F water. Pentair's IntelliChlor goes into standby below 52°F and stops on very low salt or low flow. See salt cell codes.
- Chlorine demand went up after heat, rain or heavy use. Hayward notes most owners turn their output up in peak summer.
Getting it back
- Keep everyone out of the water.
- Test free chlorine and pH (CDC: at least 1 ppm free chlorine, or 2 ppm with stabilizer, and pH 7.0 to 7.8).
- Get the pump running and the filter clean, and run the pump longer than normal while it clears.
- Follow the label on any shock or algaecide, and never mix chemicals.
- Clean or backwash the filter as it loads up, watching the pressure gauge.
When it's a tech job
If the pump, timer, automation or chlorinator isn't running the way it should, that's the part to fix, or the pool will go green again. A short video call can find out which.
Common questions
Why did my pool turn green overnight?
Algae grows fast when chlorine drops to zero, especially in warm weather. Common reasons are a pump or chlorinator that stopped, a salt cell that's dirty or low on salt, or a big jump in chlorine demand after heat or rain.
Why is my salt pool green?
Often the salt system isn't making chlorine. Check its lights for no flow, low or high salt, inspect cell or cold-water standby. Then test the water, since output may just need turning up in hot weather.
Is it safe to swim in a green pool?
No. Stay out until the water is clear, you can see the bottom, and chlorine and pH are back in range.
Related guides
Cloudy pool water
Test first. Cloudy water is usually chlorine, pH or filtration.
Read the guideSalt cell / chlorinator codes
No Flow, Check Salt, Inspect Cell and what the IntelliChlor LEDs mean.
Read the guideFilter pressure high or low
The gauge tells you when to clean the filter, and when something upstream is wrong.
Read the guidePump not priming
Pump runs but the basket won't fill. Almost always air or water level.
Read the guideSources
- CDC Healthy Swimming: Home pool and hot tub water treatment and testing (chlorine and pH)
- Hayward, AquaRite salt chlorination owner's manual (092540 Rev G): water chemistry, indicator LEDs, cell inspection and troubleshooting
- Pentair, IntelliChlor salt chlorine generator (IC15/IC20/IC40/IC60) installation and user's guide: salt, cell, flow and cold-water LEDs
Brand names belong to their owners. Pool Helpline isn't affiliated with or endorsed by any manufacturer. Steps and codes vary by model and year, so always check your own owner's manual.
