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Thread: Is this Algae?

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    Is this Algae?

    Sorry this is so long, but I figured more information was better.

    On Thursday, I noticed some slight green blooming on the walls at the waterline and just below mostly all around my pool, around the return jets and Polaris connector, and on the "seats" under my waterfalls.

    Friday I shocked to 15 FC per Pool School and Pool Calculator. Scrubbed that day with a brush (that was rough, as some of the algae was stubborn). Noticed that on the horizontal surfaces (steps, seats, etc.), when I brushed, clouds of grey would come up. Nothing was visible until I brushed (the surface is itself a grey color), but I could brush the grey stuff off into the deeper parts of the pool. So I did that.

    On Saturday morning, FC was at 14, but there were still a few spots here or there that I had missed, so I rescrubbed and added chlorine. Again I had the big grey clouds when I brushed the steps, etc. I added a little too much chlorine this time, and FC went to 21.

    Yesterday morning FC was 15, and I could find no green algae spots anywhere. But when I brushed the steps I got the clouds again. So I got concerned. I poured in enough bleach to get the pool to 25 FC. This morning the FC was 21, and I still have clouds when I brush the steps.

    Is this algae or something else? The color of the stuff on the bottom is not discernible from my medium-grey pool bottom, but when I brush it looks like grey with a slight brown tinge. The particles are extremely fine - like if I had mixed water and mud until the mud was fully dissolved and then poured it into the pool. It will cloud the pool in the brushed spots for 5-10 minutes then clear up. Running the pump for 72 hours continuously made no difference.

    Any thoughts on what I've got? Thanks in advance.
    IG plaster pool, 16000 gallons, Hayward DE6020 filter (120GPM) , 2.0 HP 230v single speed 1.3SR motor on Sta-Rite Max-E-Glas 1 pump, Polaris 280 (with Polaris 1.5 HP booster pump), spa.

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    Re: Is this Algae?

    Oh, forgot to mention. The spa had algae on the walls when I started. It is now crystal clear and sparkling, with none of this cloud stuff.
    IG plaster pool, 16000 gallons, Hayward DE6020 filter (120GPM) , 2.0 HP 230v single speed 1.3SR motor on Sta-Rite Max-E-Glas 1 pump, Polaris 280 (with Polaris 1.5 HP booster pump), spa.

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    Butterfly's Avatar
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    Re: Is this Algae?

    The clouding when brushing is prob dead algae.

    Can you post a full set of test results?

    Have you checked/cleaned your filter?
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    Mod Squad JohnT's Avatar
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    Re: Is this Algae?

    Could be dead algae. As long as your chlorine is holding reasonably well, I'd just run the cleaner and keep your pump running 24/7 to get rid of the leftovers.
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  5. Back To Top    #5

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    Re: Is this Algae?

    Thanks for the replies.

    Here are the full set of results:

    pH - 8.2+ (I understand extreme shock can make this read high - previously it was 7.6-7.8)
    FC - 21
    CC - 0
    TA - 70-80
    CH - 460
    CYA 35-40

    If it's dead algae does that mean my filter's not doing a good job or that for some reason this stuff is not making it to the filter? It's always in the same places.

    Filter was backwashed and new DE added 10 days ago. I figured I'd do the backwash again when the shock was over. I bough the house right before Christmas and the previous owner told me the filter was cleaned in October. The pool was unused from late Nov to the end of Feb, but not shut down. Number on the filter pressure gauge is actually sightly below the "green" needle. Before the backwash it was close to the "red" needle. After I did the backwash I added 6.0 lbs DE to the 7.5 lb capacity filter, but since you mention it it does concern me that I'm below the "green" needle.
    IG plaster pool, 16000 gallons, Hayward DE6020 filter (120GPM) , 2.0 HP 230v single speed 1.3SR motor on Sta-Rite Max-E-Glas 1 pump, Polaris 280 (with Polaris 1.5 HP booster pump), spa.

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    In the Industry


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    Re: Is this Algae?

    It's always in the same places
    Just out of curiosity, how long ago was your pool built/installed?

    If this 'dust' is the same color as your plaster, maybe it's chalking from the pool surface? It would make sense for chalking to occur on horizontal surfaces like steps because it will be in direct sunlight more than other areas of the pool.

    If it is chalking, I would still just run your cleaner and pump to clean it out.

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    Re: Is this Algae?

    Unfortunately, the pool was built in the 80s and resurfaced in about 2006.
    IG plaster pool, 16000 gallons, Hayward DE6020 filter (120GPM) , 2.0 HP 230v single speed 1.3SR motor on Sta-Rite Max-E-Glas 1 pump, Polaris 280 (with Polaris 1.5 HP booster pump), spa.

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    Johnl's Avatar
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    Re: Is this Algae?

    Given your hardness level, I was wondering if it's calcium scale.
    23K Gunite IG Pool
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    Re: Is this Algae?

    I know nothing about scaling, but the stuff is not "sticking" at all. It's just too heavy to float for long.

    The Pool Calculator says I'm below the CSI for scaling, FWIW.
    IG plaster pool, 16000 gallons, Hayward DE6020 filter (120GPM) , 2.0 HP 230v single speed 1.3SR motor on Sta-Rite Max-E-Glas 1 pump, Polaris 280 (with Polaris 1.5 HP booster pump), spa.

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