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Thread: CYA fluctuation

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    lkalred's Avatar
    Join Date
    May 2013
    Houlton, Maine

    CYA fluctuation

    New pool owner, first summer.

    Have experienced CYA fluctuation with rain dilution, evaporation in N Texas heat calls for refilling often, resulting in CYA fluctuation. CH also going down with dilution. Was advised earlier that rain should have no effect on chem levels. How is it possible to get significant dilution and have no change in chems?
    Is this a product of my testing techniques or is this normal? Forecast calls for multiple inches of rain in next few days. Maybe this is just the result of owning a pool in TX. Should I expect to have to add CYA? Again?

    Todays numbers:

    CYA-50 (was 40, added 2 lbs 3 days ago)

    Water is clear to the point of can tell heads or tails on dime in deep end. Thank you TFP!

    250Gal, portable spa, K-2006

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    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: CYA fluctuation

    The water in your pool evaporates but the CH and CYA do not. Once you refill, those two parameters return to normal.

    Rainfall does dilute them but not nearly as much as many people think. A 48" deep pool that gets 2" of rain dilutes by 4%, etc.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3

    Join Date
    Jun 2012
    Howell, NJ

    Re: CYA fluctuation

    The only way rain can make it go down is if the pool gets to the point of overflowing. But it would take a lot of overflow to make a noticeable effect.
    7 year old ~13,500 gal 24' AGP with 1.5 hp Proline pump, 150 sqft Pleatco cartridge, filled with well water with pH of about 4.5.
    Wanda the Whale pool vacuum, home made heater, Taylor K-2006
    Cloudy Pool? 1) Order test kit. 2) Follow SLAM
    New to TFPC? Read Pool School a few times, then post questions. PoolMath will help with chemical additions.

  4. Back To Top    #4
    harleysilo's Avatar
    Join Date
    Mar 2012
    North Georgia

    Re: CYA fluctuation

    If you are draining water from your pool you will be draining out some CYA and Ca.
    18'x43' Sport Pool
    19,000 Gallons Vinyl Liner 3'-3.5'-4'
    SWCG and D.E. Filter
    Test Kits - Pool Calculator - Chlorine/CYA Chart - Pool School

    Secret Weapon for Pool Chemistry Testing

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