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Thread: What depletes CYA?

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    Join Date
    Mar 2013
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    NW GA
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    What depletes CYA?

    My test kit came in Saturday. (Baaaaad idea y'all for me to have test kits. I want to test everything every day multiple times a day just to see what's going on!!)

    First test 4/13
    FC - 0
    TC - 1
    pH - 8.0
    TA - 130
    CH - 120
    CYA - 0
    Salt - 2320

    I added:
    5lbs trichlor
    10lbs stabilizer (CYA)
    1 quart muratic acid
    8x 40lb bags of salt
    And turned the return jets upward to aerate
    (Turned the swg off to let salt dissolve)
    (I added the CYA in a pair of pantyhose and hung it in front of a return jet. It was completely dissolve from the pantyhose within about 24 hours. )

    Second test 4/15
    FC - 5
    TC - 5
    pH - 7.4
    TA - 100
    CH - 120
    CYA - 40
    Salt - 3800

    So now I'll turn the swg on maybe 20% and monitor TC
    Pool calculator is telling me 6 more lbs of CYA to get to 70. At $20 per 5 pounds this stuff is expensive and I'm hoping to not have to add it often!
    What causes CYA to deplete and how often should I expect to have to add it?
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    Re: What depletes CYA?

    I haven't tested my fill water yet. More tests to run!
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    Join Date
    May 2011
    Location
    Montgomery, TX
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    176

    Re: What depletes CYA?

    most everyone on this board says only water replacement lowers cya, but I have found in my pool that hypochlorite in bleach and cal-hypo oxidizes and lowers cya to the tune of about 5-10 ppm per month.

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    JasonLion's Avatar
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    Re: What depletes CYA?

    Most people only need to add CYA once per season.

    Oxidation of CYA can happen but it is much slower than that, perhaps 2 ppm/month. Mostly CYA is lost when you replace water, for example when you backwash or winterize, and occasionally CYA will vanish over the winter.
    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

  5. Back To Top    #5

    Re: What depletes CYA?

    I'd give you some of my CYA, but it's all in the water :0
    19,500gal, Gunite, Pebbletec, Chlorine, PCC2000 cleaner, Stenner Chlorine Pump, MegaCatch Mosquito Trap

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    Re: What depletes CYA?

    Wait before you add more cya yer I recall even if disolved it can take several days to register on test
    24' 52" Above Ground
    BBB
    LOVE TFP
    TF Test kits, Pool School, Pool Calculator

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    linen's Avatar
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    Jul 2010
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    Re: What depletes CYA?

    Quote Originally Posted by imwarren
    Wait before you add more cya yer I recall even if disolved it can take several days to register on test
    This is a good point by imwarren. Adding 10 lbs to your 24000 gallon pool should raise it up 50 ppm. It can take up to a week for cya to show up. In addition, there are a couple of reasons to wait to add more, one is knowing your pool volume accurately, and two, there may have been a small amount of cya in the pool even though you read 0 (unless you just refilled the pool or know the full history of the water). I would wait to add more until ~6 days go by and test again.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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    Re: What depletes CYA?

    Okay. Thanks, y'all.
    So should I add muratic acid to lower the pH in order to keep working on TA for now?
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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    linen's Avatar
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    Re: What depletes CYA?

    If you are still at 7.4, I would continue to aerate up to 7.8, then drop it back down.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  10. Back To Top    #10

    Join Date
    Mar 2013
    Location
    NW GA
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    Re: What depletes CYA?

    Edited my sig. Measured pool depth. I had estimated 7' deep end but it's 8'. I measured the step depth too and calculated it all in pentair volume calculator.

    Just tested fill water.
    TC - 0 (good)
    pH - 7.2
    TA - 140
    I didn't test CH since my pool is fine on CH an a wide range is acceptable.
    I didn't test CYA because tap water shouldn't have any...
    So hopefully the kids can splash out any extra TA over the summer as we refill the pool!
    26900 gal IG Vinyl (18'x36', 3' shallow end and 8' deep end plus steps)
    sand filter and 2.7hp variable speed timer
    Jandy Ei SWG (2yr old)

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