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Thread: High CYA

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    High CYA

    Just took over maintenance of my pool. History of it is I bought the house last summer, hired a random pool guy for the short term as I figured that with a new house and baby at home I wouldn't have time to do everything so the pool was an easy thing to outsource.

    So now that he is gone I'm looking at the chemistry and concerned. The FC is way high, 25 or so, with a CYA of 100 or so. PH, TA, and CH all appear to be within reason. This according to my Taylor 2006 kit. I've tested several times over the past week or so and get consistent results. From what I can tell, the only way to lower the CYA is to replace water, approx 50% according to the pool calculator. Is there any downside to such a high CYA besides the proportionally high chlorine levels?

    Now on the chlorine side, any way to estimate how long it will take to go from 25 down to the 8-13 the pool calculator suggests for 100 CYA? Weeks? Months? I live in southeast Florida, screened in pool if it matters. We are heading into the rainy season here, so that may help. Or, should I attempt to chemically lower the FC?

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    dmanb2b's Avatar
    Join Date
    Apr 2009

    Re: High CYA

    Welcome to TFP

    If you can get your CYA to 70 or so, you should be fine. Coming down from 25 to 13 can happen in as few as 3-5 days. With CYA at 100, having FC in the 15-25 range won't harm things much as you are well below shock value.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: High CYA

    Welcome to TFP.

    Since you live in Fla, R/O is out, so yes replacing water is the only way to lower CYA. The biggest issues with high CYA is the high FC you have to maintain on a daily basis and if you ever needed to shock, it takes an enormous amount of bleach to get you there. And by the way, most CYA tests report more than 100 ppm as 100 ppm, so it could be much higher than that.

    In south Florida it won't take long for the FC to come down even with all that CYA in there. A few days at the most.
    Dave J. TFP Moderator
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