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Thread: Need help to determine a yellow / brownish spot

  1. Back To Top    #1

    Join Date
    Jun 2009
    Location
    Fresno CA
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    24

    Need help to determine a yellow / brownish spot

    Hi,

    I have had a yellow / brownish spot near my main drain in my pool. The spot has been there for about two years before I knew about TFP. I did not think much of it in the past since I did overnight loss test and only lost about 0.5 on my FC.

    What is the best way to determine what kind of spot I have? Sorry I did not include pictures but as soon as possible I can post. I have had proper FC levels for the past two years. Could it be mustard algae and what does it look like?


    FC 20.0 (currently shocking pool)
    PH 7.6
    TA 80
    CH 420
    CYA 40

    Any help is appreciated.

    Dave
    20K gal, 15X30, IG, Plaster, Pentair VF-3050 Intelliflo Pump, Pentair Clean&Clear Cartridge Filter, SWG

  2. Back To Top    #2
    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    37,879

    Re: Need help to determine a yellow / brownish spot

    Try putting a vitamin C tablet on the spot for 30 seconds to a minute and see what happens. If it is an iron stain, it should vanish, or lighten significantly, where the vitamin C tablet was.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3

    Join Date
    Jun 2009
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    Fresno CA
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    Re: Need help to determine a yellow / brownish spot

    Ok, I will place vitamin C tablet and see what happens. It is in the deep end about 7 ft any recommendations on which kind of tablets or it does not matter?

    Thanks,

    Dave
    20K gal, 15X30, IG, Plaster, Pentair VF-3050 Intelliflo Pump, Pentair Clean&Clear Cartridge Filter, SWG

  4. Back To Top    #4
    Butterfly's Avatar
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    May 2007
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    South Carolina
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    Re: Need help to determine a yellow / brownish spot

    Cheap Vitimin C. - the cheap tabs don't have a protected coating that takes time to dissolve.
    Since it is that far down, you might want to crush some in a sock and use a pole to hold it on the stain for a minute or so.
    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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  5. Back To Top    #5

    Join Date
    Jun 2009
    Location
    Fresno CA
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    Update! Re: Need help to determine a yellow / brownish spot

    Hi everyone,

    Just an update. I placed some vitamin C tablets in a sock and held it on the spot and it faded away. Problem solved! Actually my wife bought the Vitamin C at Dollar Tree for $1.00 and it has 30 tablets.

    Thanks for all of your help!!

    Dave
    20K gal, 15X30, IG, Plaster, Pentair VF-3050 Intelliflo Pump, Pentair Clean&Clear Cartridge Filter, SWG

  6. Back To Top    #6
    Butterfly's Avatar
    Join Date
    May 2007
    Location
    South Carolina
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    10,045

    Re: Need help to determine a yellow / brownish spot

    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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