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Thread: CYA Level and Evaporation

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    CYA Level and Evaporation

    This is a simple question, but I couldn't find any previous posts referencing it. Perhaps the question is too simple. Any my pool water evaporates and is replaced, will my CYA levels drop or does evaporation simply leave less water with a higher concentration of CYA?


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    reebok's Avatar
    Join Date
    Apr 2009
    Lakeland, FL

    Re: CYA Level and Evaporation

    your level should stay the same. cya doesn't evaporate, so yes if you don't replace water you will have a higher cya, though I doubt you could measure this loss cause it should be pretty small (unless you're losing a few feet of water to evaporation and not replacing it!)
    16x32 21,000 gallon in-ground exposed aggregate, 1.5hp pump, 120 sqft catridge filter, birdcage, solar panels, aquavac tigershark qc robot.

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    Re: CYA Level and Evaporation

    Another question, does CYA sink? That is, if I turned my filter off for a day and let things settle, and then wasted water from the bottom pool drain only, would I elimate more CYA than otherwise? Do other things settle if the pool is not being filtered?

    Thank you.

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    In the Industry

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

    Re: CYA Level and Evaporation

    No. CYA doesn't sink, and it doesn't evaporate.

    The only practical way to remove it is to drain and refill, which post pool owners have to do in a series of partial drains so as not to damage the pool.
    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
    Perfectly Clear Pool Service, Find me on Facebook!

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