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Thread: Algae when closing

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    Join Date
    Jun 2007
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    Pennsylvania
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    7

    Algae when closing

    I am getting ready to close our pool. I had it plastered this summer by Anthony Sylvan. I live in PA and it is still 70 during the day and 50 at night. I left the pool get away from me a bit and it got dirty and algae grew on it in some places. I shocked it and brushed the walls repeatedly and it is pretty good for the most part except there are some light algae areas yet that don't come off with the brush. Plus this year with the new plaster I noticed a weird kind of algae that I had never seen before. They are nearly black little round circles, smaller than a dime mostly, that don't really seem to go away after I shock it. You can dive underwater and really scrub at it and it kind of goes away. My question is can I cover up the pool now and deal with it when I open it next year or should I get rid of both of these algae issues now. I am afraid the algae will stain the plaster over the winter under the cover. Below is a picture of both types of algae.

    [attachment=1:2vz5cnbf]General Algae.JPG[/attachment:2vz5cnbf]

    [attachment=0:2vz5cnbf]Black Circle Algae.JPG[/attachment:2vz5cnbf]
    Attached Images Attached Images

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    BoDarville's Avatar
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    Re: Algae when closing

    I would get rid of the algae now before you close the pool. It will be easier to do as the water gets cooler.

    Quote Originally Posted by DeweyDiablo
    Plus this year with the new plaster I noticed a weird kind of algae that I had never seen before. They are nearly black little round circles, smaller than a dime mostly, that don't really seem to go away after I shock it. You can dive underwater and really scrub at it and it kind of goes away.
    This is very likely black algae. The key to getting rid of black algae is brushing at least twice a day. The brushing will break down the black algae's protective barrier and allow the chlorine to come in direct contact with the actual algae. Keep the chlorine (FC) at shock (a.k.a., SLAM) levels until you pass all criteria in the SLAM Process. Once you pass this criteria, the water should be clear, but you might have some of these black spots remaining. Keep brushing these areas twice a day and maintain FC between the high end of the maintenance range for your CYA and the SLAM level (see Chlorine/CYA Chart) until the black algae is gone.
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    duraleigh's Avatar
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    Apr 2007
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    Re: Algae when closing

    I agree with Bo. Your pool has been neglected and you will have a bigger, tougher job getting rid of algae and the staining in the Spring.

    Getting your pool back in shape will be more than a one time effort......you will need to fundamentally change the way you manage your pool water or you will be constantly faced with the same issues but I am sure you know that.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Patrick_B's Avatar
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    Re: Algae when closing

    You've gotten solid advice from two of our best, so please take it to heart.

    When you say you "shock" the pool it hasn't done anything because the FC must remain at a high level
    for an extended period. How long on that just depends. It is different in every pool, but your situation is
    one we see over and over. To "shock" is really not helpful, or accurate unless you hold it at shock level until everything,
    and I mean everything is dead. As Bo mentioned, we call this the SLAM process. It takes time and lengthy exposure to
    high FC to do the job.
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