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Thread: CYA Disappearing....

  1. Back To Top    #1

    Join Date
    Aug 2014
    Florissant, MO

    CYA Disappearing....

    I thought cyanuric acid stayed in the pool water but I had my cyanuric acid at 50 and now it's near zero????
    My latest readings for my swg pool is:
    FC - 1.5
    PH - 7.4
    TA - 40
    CH - 70
    CYA - 0
    Salt - 2740
    1998 Doughboy 16x28x3.5 Oval AG pool (10,300 gallons)
    Hayward Power Flo Matrix pump w/single speed-1 hp motor & Hayward EC-50 DE Filter
    Use Aqua-Check Reg & Salt Test Strips / Taylor K-2006 & TF100 / Speedster Magnetic Stirrer
    Just added Intex SWG w/ECO 8110 (15000 gallon) Pool owner since 1978.

  2. Back To Top    #2
    Mod Squad Texas Splash's Avatar
    Join Date
    Jun 2014
    South-Central Texas, Marion/San Antonio

    Re: CYA Disappearing....

    That is true, unless your FC dropped so low that ammonia began to take over and consume the CYA. I would offer the following recommendations for you to implement right away based on those readings:
    - Use the Poolmath calculator to increase TA to about 60.
    - Use regular bleach to increase FC to 10. Test to see if it holds between 5-10 after 10 minutes. If it does, then add stabilizer for a CYA target of 30 and monitor. If your FC drops to 4 or below during that 10-min test, increase FC right away and continue that process until it does hold better for 10 minutes.

    If your water is cloudy or displays any signs of algae, then once you've confirmed the FC is holding after 10 minutes go right into a TFP "SLAM" (link below). If you have any doubt about algae, perform an overnight (OCLT) test to confirm the presence of algae. Make sure the SWG is OFF during the OCLT. Hope that helps.

    Pool School - Perform the Overnight FC Loss Test (OCLT)
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3
    Mod Squad
    Join Date
    Aug 2012
    DFW, TX

    Re: CYA Disappearing....

    Yes, it is rare but possible when FC drops below normal for bacteria to grow that will consume CYA. It is important to keep FC above minimum at all times to keep the pool safe, sanitary and bacteria free. FC/CYA Chart
    TFP Moderator
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    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

  4. Back To Top    #4

    In the Industry

    Join Date
    Jun 2016

    Re: CYA Disappearing....

    Is it possible you have a leak by any chance? Your other parameters are pretty low as well...apart from salt and pH. Calcium doesn't really matter though with vinyl.

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