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Thread: which CYA test is more accurate?

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    which CYA test is more accurate?

    I became a BBB user since July 1, and use 3 lb shocks and 2 tablet during past two months. the CYA level tested by a pool store was 100 ppm on July 4. my CYA test result using TF-100 was 40-50 on July 8. The CYA level keeps the same range of 40-50 using TF-100. I went to the pool store to purchase MA and let them test water, the CYA level became 28!!. I tested two days ago, it was still 40-50.

    I think my test result is more reasonable since there is no rains during these days. Why their testing results changed that a lot?
    26,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris cleaner, cartridge filter. Located in Katy, Texas.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: which CYA test is more accurate?

    Trust your own results. There is no way CYA could have gone down as much as they said unless there was massive water replacement.

    The black dot test in the TF100 is the best one available short of rather more expensive laboratory grade tests. Pool store testing is sadly amazingly unreliable. There are some good stores out there, but there are also many bad one. The details of why their testing is bad vary depending on what kind of test kit they are using. Some stores use test strips which are especially unreliable for testing CYA. Others simply do the test wrong, even when they are using a good quality test kit.
    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

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    Join Date
    Jun 2011
    Cape Girardeau, Mo

    Re: which CYA test is more accurate?

    I think a good rule of thumb is when you own a good test kit such as the TF-100 or Taylor K-2006 is to always trust your own results and never take a sample to a pool store unless maybe you suspect metals because it always makes people second guess there self even though most pool stores results have been proven to be notoriously wrong.
    Steve Frakes
    15' X 48'' Intex Metal Frame
    Intex Sand Filter 16'' 2650 GPH
    Taylor K-2006 Test Kit
    BBB and Borated

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