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Thread: Black algae

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    Black algae

    We are in escrow to buy a home with an in ground play pool. We noticed that there are black spots and small patches of black algae sprinkled on the bottom and sides of the pool. The pool has a DE filter and also has some gizmo called an oxygen generator that appears to be in line with the filter. Can black algae be successfully treated or should I consider backing out of the purchase of an otherwise perfect home? If treatable, how do we go about the process?
    Thanks for any assistance out there.
    35k gal, sand, IG, diamond brite, Hayward Goldline T-CELL-15 Turbo SWG, Aquarite

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    BoDarville's Avatar
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    Re: Black algae

    Welcome to TFP

    Black algae can be treated, but "elbow grease" is as much a key ingredient as is chlorine. With black algae, maintaining shock level isn't the most crucial thing, it is removing layer after layer of protective crust to get at the algae underneath. The frequent brushing will expose the black algae to the elevated chlorine levels and prevent the algae from excreting waxy substances that inhibit chlorine being able to get at it. Suggest getting a stainless steel brush. As for chlorine, you need to keep it at the high end of the recommended range while brushing several times a day. Once you move in, post a series of test results and we will go from there.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

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    Mod Squad kimkats's Avatar
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    Re: Black algae

    You might want to go ahead and order a test kit so you will have it in hand when you are access to the pool to start the process. There is a link in my siggy.

    Happy house buying and moving!

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Black algae

    So it's not hopeless? I'm not going to be battling a black lagoon for the rest f my life?
    35k gal, sand, IG, diamond brite, Hayward Goldline T-CELL-15 Turbo SWG, Aquarite

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    BoDarville's Avatar
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    Re: Black algae

    No, but it will take a fair amount of effort to get rid of it. This means daily (or perhaps even twice daily for the first week or so) brushing with a stainless steel brush. That, plus maintaining chlorine levels about 50% above the suggested level for your CYA for at least the remainder of the summer will eventually get rid of it. If you follow these steps, what will likely happen is that a majority of the visible spots will disappear within a week or so. Some persistent spots may require spot brushing with a small stainless steel brush and rubbing a trichlor puck directly on the stain to get those areas to disappear. From there, you will need to keep an eye out for any new spots that may reappear (if this occurs, it should be in isolated spots). For any that do occur, brush that area with a small stainless steel brush and rub a trichlor puck on that area only. It will eventually go away. Several members have defeated black algae and you can too.

    So, here's the equipment you will need if you decide to go forward with purchasing the house:
    • 1. A large stainless steel brush for brushing the entire pool surface
      2. A small stainless steel brush for spot-brushing stubborn areas where black algae spots either persist or reappear.
      3. Bleach - plain, unscented, and without any thickeners or other additives. Stock up now.
      4. A few trichlor pucks
      5. A good Test Kit.
      6. Elbow grease - you supply that


    Once you move in, run a full series of tests and we will get you started.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

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    Re: Black algae

    Thanks so much for your input! Sounds like it will a test of wills for awhile.
    35k gal, sand, IG, diamond brite, Hayward Goldline T-CELL-15 Turbo SWG, Aquarite

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    BoDarville's Avatar
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    Re: Black algae

    Quote Originally Posted by Liviaflood
    Thanks so much for your input! Sounds like it will a test of wills for awhile.
    That's exactly it, but you will prevail.

    Assuming you go forward with the purchase, I'm not sure how far off you would be from closing. Therefore, I will make one clarification on the equipment: Hold off on getting the bleach and trichlor pucks until you are within a week or so from closing. You want the freshest possible product (bleach strength can degrade if left sitting around for too long, especially during the summer heat). You can get the remainder of the equipment at any time, however.
    Gold Supporter, TFP Lifetime Supporter, 26,680 gal Plaster IGP 3.5 - 10' depth / Attached Waterfall Spa, Manually Chlorinated, Triton Sand Filter, 1.5 HP * 1.1 SF = 1.65 SFHP 1-speed Pentair WhisperFlo WF-26 Pump, 400K BTU NG Teledyne Laars Series One Heater, Polaris 360, Test Kit Comparison, Chlorine/CYA Chart, SLAMing Your Pool, OCLT
    A good test kit is an investment, not an expense.

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