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Thread: Yellow stains on fiberglass

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    Yellow stains on fiberglass

    Please start your own thread Thanks, Butterfly
    Split from here: post489020.html#p489020

    Hello, new here also. And having the same problem on our fiberglass pool. The vitamin C tab does remove the stain, but brushing and rubbing the stain with organic cleaner does nothing. The pool store that tested the water said that there is NO metals in my water. So what is causing the stain? I have a 6 inch deep ring around the entire pool, probably the winter water line, and some tiny rust spots on the princess deck. Should I treat it like a metal stain and add ascorbic acid since the Vitamin C works?

    Pool Test:
    FAC = 3.7
    TC = 3.86
    CC = 0.16
    PH = 8 (have added PH decreaser since this test)
    TA = 143 (but just raised it)
    Cal Hard = 208
    Cyanuric Acid = 32
    SALT = 3000
    Saturation Index = 0.7
    All of the 6 metals/phosphates read 0

    Pool is an 15 x 30 IG Fiberglass, 11,000 gal, with heater and Salt Water Chlorinator
    IG, Fiberglass, 15 x 32, 11K gal, Hayward Super Pump HP 1, Hayward Cartridge Filter, AquaRite SWG, Hayward Titanium Heater

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    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Yellow stains on fiberglass

    Welcome to the forum.

    Should I treat it like a metal stain and add ascorbic acid since the Vitamin C works?
    Yes, definitely.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Yellow stains on fiberglass

    We have instructions in Pool School for doing an Ascorbic Acid Treatment.

    If you have a small amount of staining, you could crush Vitamin C tabs in a sock and move it around on the stain. Large amount of staining would likely need the complete AA treatment.

    Welcome to the forum
    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.

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