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Thread: White stains on fiberglass

  1. Back To Top    #1

    Join Date
    Oct 2008
    Location
    Pennsylvania
    Posts
    4

    White stains on fiberglass

    I am accumulating two or three white stains on my fiberglass pool every day. Have been shocking for the last week. 2 lbs of HTH shock every night, and can not keep FC up.
    I have been mixing shock powder in water before broadcasting in pool, and following up with pool brushing so as not to have any undesolved powder laying on bottom.
    Any ideas on the stains. I want to prevent as much as possible. I have brushed stains with no effect.


    Latest test read is:
    TC -1
    FC -0
    TH -250
    PH - 7.3
    TA - 140
    CA - 40-50
    San Juan light blue fiberglass pool
    13,500 gallon IG
    Hayward Cartridge Filter
    Goldline SWG

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887

    Re: White stains on fiberglass

    HTH shock tends to be cal-hypo which adds chlorine to the pool. White stains tend to be calcium scaling, which is the result of high calcium levels in the water.

    From your test results, it looks like you are using test strips. Test strips are not especially reliable. You will be much better off if you get a top quality test kit. You can't take care of the vanishing chlorine problem until you find out what your CYA level really is. Test strip CYA tests are especially prone to dramatic mistakes.
    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
    Oct 2008
    Location
    Pennsylvania
    Posts
    4

    Re: White stains on fiberglass

    JasonLion,
    Thank you for your response.

    I presently am using a Taylor K-1004 test kit for all but CYA. For that I have been using both the general Aquacheck strips plus the Aquacheck CA strip. Both have shown the same. I will be on my way in the next day or so to get a full functtion test kit. In the meantime, is there any thing I should do to reduce the staining? Are the stains permanent?
    Thanks again.
    San Juan light blue fiberglass pool
    13,500 gallon IG
    Hayward Cartridge Filter
    Goldline SWG

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