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Thread: CYA Test not accurate over 100 ppm?

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    Join Date
    Jun 2013
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    CYA Test not accurate over 100 ppm?

    I see a lot of posts saying CYA test over 100 ppm is not accurate. But what about after diluting pool water with well water that is 0 ppm CYA and then testing and double the result. Is that an accurate method? My kit has been testing right at 100, so I diluted with well water and I get the result of 50 ppm. Seems accurate, but am I wrong?
    - Max
    __________________________________
    20k gal, inground vinyl, 1 1/2 HP Hayward SuperPump, HW Veriflow XL Sand Filter, Hayward Aqua Rite T-Cell-9, AquaComfort Heat Pump ACT-1100
    Hayward TigerShark robotic cleaner

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    Administrator Leebo's Avatar
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    Re: CYA Test not accurate over 100 ppm?

    It does lose some accuracy by doing that....but not enough to matter in this case. I would still suggest you drain 1/2 the water to lower your CYA level, refill, then retest.

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    JasonLion's Avatar
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    Re: CYA Test not accurate over 100 ppm?

    When doing the CYA test with 1 to 1 dilution the precision drops to +-30 (or worse), which is fine for estimating how much water replacement you need to do, but not good enough for much else.
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    Isaac-1's Avatar
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    Re: CYA Test not accurate over 100 ppm?

    Just because your water might really be at 100 ppm CYA, does not mean that another sample that was for example 140 ppm CYA would not also read 100 ppm CYA on the undiluted test. As this is more of an out of range condition than a true accuracy one.
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    Join Date
    Jun 2013
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    Orange County, NY
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    Re: CYA Test not accurate over 100 ppm?

    ok, thanks all.
    - Max
    __________________________________
    20k gal, inground vinyl, 1 1/2 HP Hayward SuperPump, HW Veriflow XL Sand Filter, Hayward Aqua Rite T-Cell-9, AquaComfort Heat Pump ACT-1100
    Hayward TigerShark robotic cleaner

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