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Why Does My Pool Keep Turning Green?

Recurring algae can be a problem this time of the year. There can be several contributing factors, heat, rain, letting chemicals get out of balance, and even transfer form one pool to another. Recurring algae is usually Mustard Algae. It is a yellowish green color that usually starts growing on the pool walls and on the pool floor.  It will then turn the pool water green. So how do you get rid of mustard Algae and keep it from coming back? First vacuum the pool on the waste setting. Mustard Algae is resistant to the normal chlorine levels so to get rid of Mustard Algae you can use a Yellow Out type product. To keep the Mustard Algae from returning to your pool you should use copper algaecide. Copper algaecide should be used as per the manufacturer instructions and should not be used during high levels of chlorine to prevent staining. Use clarifier to help filter out the algae and Metal Out or Demineralizer to prevent staining.

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  1. Tanya Urdialez says:

    myspool floor is green. pool just serviced about a week ago. cleaners said they used all the proper chemicals. i’ve been using vacume. pool man came back today tested water. says all, not under or over chemicalized. please help! don’t what else to do.

  2. Genny says:

    It may be several reason why it is turning green. Visit for more information on why it is doing that.

  3. Albert Martin says:

    This has happened to me in the past and I added stabilizer to keep the chemicals in the pool. Once the pool is stabilized the chemicals will maintain their levels and it should clear up.

  4. The Swimming Pool Butler says:

    We have a pool service company in Arizona and run into this problem all the time. The chemical levels in your pool can be right where they need to be and mustard algae can still easily form. Another factor that breeds mustard algae can be phosphates coming from leaves and debrees entering your pool as well as from your tap water. To get rid of it the first thing we do is bump up the chlorine level and brush the pool walls and steps. This will release it from the pool walls, allow the chlorine to neutralize it and filter it out. If this doesnt work than we use an algecide which will zap it right away. We use HASA Algecide. Hope this helps.

  5. ECOsmarte says:

    If all circulation and filtration components are working properly I would also highly recommend testing phosphates. With more and more municipalities adding phosphates directly to the source water and high levels in rain water we are experiencing high levels all over the US. Contrary to the above comment all of the chlorine and algaecide in world will not neutralize the phosphate. You must use a phosphate specific eliminator.


  6. Elmo says:

    Exceptional piece of writing, I am checking back more often to look around for improvements.

  7. James says:

    i have a problem our pool was doing great then all of a sudden it was green Ph was good ,Chlorine was good . Swimming pool place said 6 gallons of shock 12,000 gallon pool plus 14 ounces super algaecide did that it looked vacuumed to waste as recommended it was after adding more water ok not real clear then turned green again- then back up to pool store 6 gallons more still waiting for it to clear up . Wondering if it is picking up copper from our city water supply

  8. Janet Walker says:

    For the past month and half we have not been able to get our pool water clear. We have tested water weekly at pool store and have been adding something every week. The ph started out low and water turned green. Now ph is testing high and water is still green. No apparant algea on sides of pool, and can not see the bottom. We have changed out pump and sand filter with new sand and still having same problem. Just wondering if we could have added so many chemicles that it done something to the water and can not get it right now.

  9. Janet Walker says:

    Well, think we got our problelm solved. Had been fighting green water for awhile now. We used a product called revive. Awesome product! We now have a beautiful pool again. Hope this will help someone else dealing with the same problem.

  10. Sometimes poor or misdirected water circulation can prevent the pool chemicals from removing all of the algae. You must also use the recommended dosage of algaecide called for by the manufacturer or risk not killing all the algae even though you do not see any.

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