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Thread: Is this black algae? What do I do?!

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    Join Date
    May 2016

    Is this black algae? What do I do?!

    I have what may be black algae all over the walls of my 30' round above-ground pool. I have used an algae killer for black algae and 7 bags of shock. I tried brushing the walls after my pool had cycled for three hours, but although the algae is coming off into the pool, the black spots remain on the walls. Will these dark spots go away, or will I have to get a new liner? Is this black algae or something else? Help, please!
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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Is this black algae? What do I do?!


    No, not black algae. Black algae looks like polka dots or freckles. You just have algae and maybe some staining from it.

    What you need to do is what we call a SLAM Forget shock powders and miracle snake oils and algaecides. It's bleach you'll be wanting. And a proper test kit so you know how much to add at one time.

    It's all explained in the SLAM article, and you can also see how it works with real people in some of these threads.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Is this black algae? What do I do?!

    Richard320 has covered the bases. You simply are not keeping chlorine in your pool. read "The ABC's of Pool Water Chemistry" up in Pool School. That the textbook from which comes all of the things we teach. When you get that digested, you'll need one of the good testkits (you can't find it locally) and then let us walk you through the SLAM procedure.

    That process will reduce the staining and continued elevated FC levels will eliminate them.....maybe 100%.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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