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Thread: whitish band at waterline

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    whitish band at waterline

    Dear All,

    In the past two days, a whitish band has developed along the waterline of our pool. Can anyone shed light on what has caused it, and how to possibly get rid of it? The wall surface is painted concrete, so I'm concerned about serious scrubbing). See the picture below, and below that, numbers from yesterday's water test (TF100 kit).

    all best,

    Numbers from yesterday's water test (I had a 1 ppm FC loss overnight prior to the test):

    FC: 4
    CC: .5
    TC: 4.5
    pH: 7.3
    T/A: 150 (down from 170 from last week's test)
    CH: 210
    CYA: 40 (note: CYA should now be at @50, as I added 14 oz. stablizer after the test)
    11,500 gal. rectangular cement, 11 x 28 (built c1930); Hayward S180T sand filter; Hayward Max-Flo II 3/4 HP pump

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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: whitish band at waterline

    Well, it's pretty much guesswork, but I would say you have some Calcium coming out of solution.

    Your CH is not too high and there is nothing in your numbers that would indicate a problem.

    It looks like it will take some brushing, scrubbing to remove. (I hear you about the painted surface) I do it sooner rather than later.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    frustratedpoolmom's Avatar
    Join Date
    May 2007
    SWSuburban Chicago, IL

    Re: whitish band at waterline

    Where's the water?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner

  4. Back To Top    #4

    Re: whitish band at waterline

    Quote Originally Posted by frustratedpoolmom
    Where's the water?
    It *is* sort of hard to tell, isn't it? There's a leaf floating along the waterline, however.
    11,500 gal. rectangular cement, 11 x 28 (built c1930); Hayward S180T sand filter; Hayward Max-Flo II 3/4 HP pump

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