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Thread: Algae Problem

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    Join Date
    Jun 2015
    Grand Rapids, MI

    Algae Problem

    I got some green algae in my pool after being gone for a few days. I started the SLAM process two days, ago, keeping my FC level above 16 based on CYA of 40 and running the pump 24/7. Last night I did an OCLT and there was no loss of chlorine during the night - CC was 0.5 or less. I can see green algae on the bottom, so I know it is in there. I thought the FC level would for sure be lower because it would be used up eating the algae. So why would the FC level stay constant overnight? Could it be that the algae is already dead? I thought it would turn more of a gray color if it was dead.

    And a somewhat unrelated question: Once the algae is dead I would like to get it cleaned out ASAP. I have researched a bit online and found that the fastest way is to add a flocculant to settle it all to the bottom, then vacuum it up. What do you all think of that method?
    18x36 IG vinyl liner. 29,000 gallons (estimate based on 18x36, 8.5 feet in deep end). Hayward pump, sand filter and heater.

  2. Back To Top    #2
    Mod Squad tim5055's Avatar
    Join Date
    May 2014
    Franklin, NC

    Re: Algae Problem

    Have you been brushing the pool, concentrating on the visible algae? Algae can be protected by a,biofilm that the brushing breaks up.

    We do not recommend floculants as they can actually make the problem worse is some situations. With your sand filter you can add little DE to allow it to filter smaller particles. The instructions are in Pool School.
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  3. Back To Top    #3

    In the Industry

    Donldson's Avatar
    Join Date
    Jun 2009
    NW Ohio

    Re: Algae Problem

    What you are experiencing is why there are 3 criteria for passing a SLAM. You may have passed your OCLT and your CC may be low, but if you see algae your pool is not clear. As Tim said, brush it up to make sure the chlorine is getting to it (daily brushing or vacuuming is specifically instructed in the SLAM procedures).

    Using floc has too many possible issues if not used exactly right, including possibly ruining your filter. There is no need, once you kill the algae it will filter out.
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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