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Thread: Need help understanding high CYA and TA relationship

  1. Back To Top    #1

    Join Date
    May 2014
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    San Diego, CA
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    Need help understanding high CYA and TA relationship

    Hello,

    I would like to thank all of you for your previous help. On your recommendation, I did buy the Taylor test kit, followed your instructions on shocking, got rid of my algae swamp and now my pool is now crystal clear!

    Luckily, my pool is pretty small, so I was able to get enough chlorine into it without breaking the bank. Thanks again

    My readings are:

    FC - 8 (I'll add more tonight)
    CC - .5
    pH - 7.4
    CH - 550
    CYA - 200 (using the dilution method)

    It will be about 2 more weeks before we are able to drain and refill the pool due to the high CYA.

    This is where I'm a little confused.......

    The Taylor booklet talks about a CYA factor to be used in calculating the TA if the CYA is high.

    With the test kit, my TA is 130. If I use the equation that they recommend, my TA would be 70. This does make a difference in my CSI being balanced.

    Would I be correct in using the TA of 70?
    Appx 11,000 gallon in ground plaster pool with spa. Sta-rite System 3 Filtration System, 300 sq ft cartridge filter. Max-E-Glas 1.5 hp pump, Baracuda G3 automatic pool cleaner.

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    svenpup's Avatar
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    Re: Need help understanding high CYA and TA relationship

    The short answer is forget about adjusted TA.

    There is tons of discussion here including this topic (specifically posts 3 & 4 from Jason and chem geek).
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

  3. Back To Top    #3

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    Re: Need help understanding high CYA and TA relationship

    Thanks for the quick response. I did read through some of those posts earlier, but they weren't quite addressing a CYA as high as mine (as far as I could see).

    Just wanted to make sure. Your advice is much appreciated
    Appx 11,000 gallon in ground plaster pool with spa. Sta-rite System 3 Filtration System, 300 sq ft cartridge filter. Max-E-Glas 1.5 hp pump, Baracuda G3 automatic pool cleaner.

  4. Back To Top    #4

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    Re: Need help understanding high CYA and TA relationship

    Is the CYA 200 from a 50% dilution or a 25% dilution?
    CYA 100 is the maximum detectable, if it showed "100" with a 50% dilution, it may be even higher.
    If it showed "50" with a 25% dilution, then CYA 200 will be the correct ballpark.

  5. Back To Top    #5

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    Re: Need help understanding high CYA and TA relationship

    I did a 50% dilution. Using the Taylor K2006 kit, I got right up to the 100 mark on the tube. Without the dilution, I fill the tube up about 3/4 inch before the black dot disappears. I will try a 25% dilution.

    Either way, my CYA is astronomical. If I use the formula to calculate a TA of 70, then my CSI is not in balance with the risk of plaster corrosion.

    If I plug a TA of 70 into the pool math calculator, is says that I need to add about 3.25 lbs of baking soda to bring the TA up and the CSI into balance.
    My pool is about 20 years old, and the plaster is just in ok shape. Is there really any risk involved if I go ahead and add the baking soda? We will be draining in 2 weeks and this will hopefully put an end to the CYA problem.

    NO MORE PUCKS AND DICHLOR!
    Appx 11,000 gallon in ground plaster pool with spa. Sta-rite System 3 Filtration System, 300 sq ft cartridge filter. Max-E-Glas 1.5 hp pump, Baracuda G3 automatic pool cleaner.

  6. Back To Top    #6
    JasonLion's Avatar
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    Re: Need help understanding high CYA and TA relationship

    If you are using PoolMath to calculate CSI, you always want to use the TA reading directly from the test kit. PoolMath will make any required adjustments internally. Adjusted TA is only used when calculating LSI, an older less accurate approximation designed to be easy to calculate by hand.
    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

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    Re: Need help understanding high CYA and TA relationship

    With draining in 2 weeks ... just worry about your CL and pH. I honestly wouldn't wast another CYA test on it. You are going to need the reagent if you are doing partials and it doesn't matter if you are doing a full drain.
    TFP Moderator Chris V. ~16K Pool & Spa, 48NSF DE, IG Plaster Circa 2000, Intermatic PE653, Challenger pump with a 2 speed B2984, 20gal stenner chlorine injection, Houston, TX
    One cannot follow Islam and Christianity at the same time, nor can one follow pool store methods and TFP at the same time.
    Pool School -- Pool Math -- TF-Test Kit

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    Re: Need help understanding high CYA and TA relationship

    Great!

    Thank all of you for your help!
    Appx 11,000 gallon in ground plaster pool with spa. Sta-rite System 3 Filtration System, 300 sq ft cartridge filter. Max-E-Glas 1.5 hp pump, Baracuda G3 automatic pool cleaner.

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