What causes green water or discolored water?
Green or discolored water is usually caused by algae growth or metals in the water.
- Algae can develop when sanitizer levels are too low and may appear green, yellow, black or pink
- Metals such as iron, copper or manganese can cause water to turn green, blue, brown, yellow or black, especially when water chemistry is out of balance or after shocking the pool
A good clue is timing: if the water gradually turns green, algae is often the cause. If the water changes color suddenly after adding chlorine or filling the pool, metals may be the culprit.
Testing your water and maintaining proper sanitizer levels, pH and filtration can help prevent both algae and metal-related discoloration.
How to Fix Algae
- Keep the water moving
Run your pool circulation system 24 hours a day while treating algae. - Shock the pool
Raise the chlorine level to about 3–5 ppm using a chlorine shock. - Balance the pH
Keep your pH between 7.2 and 7.8 for best results. - Brush and vacuum often
Scrub pool surfaces and vacuum algae at least twice daily. - Clean the filter
After brushing or vacuuming, clean or backwash the filter to remove dead algae. - Add an algaecide
We recommend FROG® Algae Gone® – a simple pod you drop in the skimmer for fast and effective results.
How to Prevent Algae
- Keep pH in range
Maintain a pH of 7.2–7.8 at all times. - Maintain proper chlorine levels
Replace your chlorine cartridge regularly to keep levels at 0.5–1.0 ppm. - Check your equipment
Make sure the pump, skimmer, and filter are clear and working properly. - Keep debris out
Remove leaves, bugs, and other organic material from the pool. - Shock when needed
Always shock the pool after heavy use or rainstorms. - Avoid fertilizers nearby
Fertilizer can feed algae, so keep it away from your pool. - Use a preventative treatment
Add FROG® 90-Day Algae Barrier® for extra protection.
