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Thread: Recurring algae

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    Recurring algae

    Have a problem with recurring algae; has been a problem last 3 years and seems worse this summer. Never had any problems before that (for 25 years), and am following same maintenance as before. What happens -- green algae shows up on walls and bottom of pool; I shock, brush entire pool and then vacuum dead algae to waste over next day or two. 7-10 days later, starts all over again with new green algae on walls, pool bottom. This latest cycle, I have been following TFP's advice on how to shock, maintaining shock FC at greater than 28 (CYA is 60 - 70) and testing early in morning for any FC loss. Have had drop of 3-4 FC ppm each of last 2 mornings, although water is clear with no visible algae. I have noticed areas of my liner (23 years old) which appear to have a slight greenish color (it's supposed to be blue) and wonder if algae could have become ingrained in the liner? I'm using 3-inch tabs for daily chlorination (via inline chlorinator which I just replaced), and use 6% bleach to shock. Other readings: ph 7.0, TA 70, CYA 60-70. I am at a complete loss!! HELP!
    20,000 gallons, IG vinyl, Hayward S-200 sand filter, Hayward 3/4 HP pump, NJ location

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    Mod Squad JohnT's Avatar
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    Re: Recurring algae

    Welcome to TFP!

    The liner can get stained from algae, but the high chlorine level should clear it up.

    Tablet chlorinators tend to be problematic, and you may not have been maintaining sufficient chlorine recently. Stick with the shock until the chlorine holds overnight, and you will win.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Butterfly's Avatar
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    Re: Recurring algae

    Welcome

    Shock using the TFP method, until you meet all three criteria to prove that you are done shocking.
    See red lines in my sig.

    Be sure to seek out any algae hiding place like ladders and light niches!
    And, brush, brush, brush.

    As JohnT said, you can and will win this battle

    Time to stop with the tabs and use only bleach/liquid chlorine.
    Your CYA is already above recommended levels.
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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    Re: Recurring algae

    On 3rd morning of my shock treatment, there was no FC loss so I'm hoping that takes care of it! Thanks for the help!
    20,000 gallons, IG vinyl, Hayward S-200 sand filter, Hayward 3/4 HP pump, NJ location

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    Butterfly's Avatar
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    Re: Recurring algae

    Okay, good. You passed all three criteria to determine that you are done shocking, right?

    For maintainance, with a CYA of 70ish, your FC should stay between 5 & 10 and never below 5.
    Use bleach/liquid chlorine to maintain the FC. Add chlorine in the evening after the sun is off the pool and dose it up to about 10FC.

    The tabs gotta go for now. You can use them later for vacations and such.
    Also, further use of the tabs could easily cause your pH/TA to crash.
    Your pH is okay at 7 and TA is just fine at 70, if you stop using tabs and make the switch to unstabilized chlorine (bleach/liquid chlorine).
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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    WestSidePool's Avatar
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    Re: Recurring algae

    Just out of curiosity since it's not listed, what kit are you using to get your test numbers?
    Eric

    IG 17x33 Grecian - Vinyl Liner (21k gallons), Hayward Pro-Grid DE 4820 filter, Hayward Super Pump, CompuPool SWG CPSC36, TF-100 Test Kit

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    Re: Recurring algae

    I'm using the TF100 test kit.
    20,000 gallons, IG vinyl, Hayward S-200 sand filter, Hayward 3/4 HP pump, NJ location

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