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Thread: Pool Turned Green even with Chlorine?

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    Join Date
    Jul 2015
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    Lake Elsinore, CA
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    Pool Turned Green even with Chlorine?

    Is it possible for your pool to turn green even when maintaining the appropriate FC to CYA?

    Prior to Shocking

    FC 7
    CC < .5
    PH 7.5
    TA 100
    CH 200
    CYA: 40
    TEMP 90 F

    After Shocking FC is about 23.
    Intex 9 x 15 x 52" 5000 gal, vinyl, Sand filter pump, Taylor K-2006

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    Richard320's Avatar
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    Re: Pool Turned Green even with Chlorine?

    If the green is from metals, sure.

    It's even possible to grow some algae on the walls despite proper FC/CYA if there's poor circulation and insufficient brushing to overcome the poor circulation.

    The whole pool turn green with algae despite adequate FC/CYA? No.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Mod Squad YippeeSkippy's Avatar
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    Re: Pool Turned Green even with Chlorine?

    Shocking is not a one time dose of medicine (contrary to what the pool store will say!) and it takes repeated doses, days, perhaps week(s) to kill off *all* the algae and prevent it reproducing like bunnies which it is wont to do. The procedure is now called a SLAM (Shock Level and Maintain) with the maintain portion being muy important.

    How long did you keep the pool FC elevated? Were you brushing daily? What did you use for the chlorine and was it fresh and strong?
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Re: Pool Turned Green even with Chlorine?

    The algae starts near the bottom corners. I was lax on brushing this week.
    Intex 9 x 15 x 52" 5000 gal, vinyl, Sand filter pump, Taylor K-2006

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    Re: Pool Turned Green even with Chlorine?

    The water looks really good now.

    On my third day of slamming. I am using Liquid Chlorine 10%. The gallon jugs I buy from Home Depot.

    The CL was bought less than 3 weeks ago. I store it in my laundry room.

    Brushing every day now before maybe two or three times a week.

    However I was maintaining the FC levels to about 6 or 7.

    That's why I was surprised when I took the cover off that there was algae present on the sides of the pool.
    Intex 9 x 15 x 52" 5000 gal, vinyl, Sand filter pump, Taylor K-2006

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    Re: Pool Turned Green even with Chlorine?

    Interesting.

    How often do you test FC and add chlorine? Daily? Twice per week? Perhaps the FC is getting low enough between doses for algae to start to grow, and then your doses up to FC=6 just wasn't enough to beat it back into submission. And every time that happened, the algae gained ground.

    How many hours a day does your pump run? If it is a two-speed pump, is it running at high speed at any time other than vacuuming?

    What is the current pressure in your sand filter, and when did you backwash last? Perhaps the filter is simply clogged, dramatically reducing the amount of circulation?

    Do your return jet have an eyeball that you can aim? If so, aiming it to one side can create a gentle circular motion to the water, ensuring even chlorination throughout the pool.

    Here's a random one: When you test FC, are you perchance using a 25ml sample, but using the 0.5 multiplier from the 10ml sample size? If this were the case, your true FC would be less than half of your measured FC.

    Yeah, too many questions. Just trying to cover all the obvious bases.
    25000-gallon semi-public IG concrete/plaster pool, Triton II sand filter
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