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Thread: CYA Level Somehow Increased

  1. #1
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    Default CYA Level Somehow Increased

    A few weeks ago I refilled my 40,000 gallon IG pool. Pool company told me to add 12 lbs of Nu-clo Conditioner & Stabilizer (consistent with Nu-Clo directions -- "For newly filled pools add 3 lbs of 10,000 gallons of water").
    Nu-Clo directions state "this dosage provides approximately 35 ppm of cyanuric acid". However somehow my CYA level is reading 95-100 as measured by Pool company and verified by my own Taylor kit readings. I double checked both readings. But if I only added 12 lbs of CYA to new water how did my CYA get to 100?

    Thanks for any insight.

  2. #2
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    Default Re: CYA Level Somehow Increased

    I forgot to mention my other readings are as follows:

    FC 4.8
    TC 4.8
    PH 7.8
    Hard 250
    Alk 170
    CYA 100

    Thanks again!

  3. #3
    chem geek is offline PF Supporter Whibble Konker chem geek 4 stars chem geek 4 stars chem geek 4 stars chem geek 4 stars
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    Default Re: CYA Level Somehow Increased

    Yes, it should have added 36 ppm CYA to your pool. Maybe your pool really already had CYA in it.

  4. #4
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    Default Re: CYA Level Somehow Increased

    thanks for response chem_geek.

    I had totally drained the pool dry to fix a problem with liner so I'm not sure where the extra CYA could have come from. A real mystery.

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    Default Re: CYA Level Somehow Increased

    The obvious possibility is that your pool isn't 40,000 gallons. Most pool companies overstate the capacity for some reason. How big is the pool dimension-wise?

  6. #6
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    Default Re: CYA Level Somehow Increased

    Thanks for response JohnT

    Dimensions are 22x27x45 Lagoon
    40" in shallow end and 8' in deep end

  7. #7
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    Default Re: CYA Level Somehow Increased

    Quote Originally Posted by CJDahl View Post
    Thanks for response JohnT

    Dimensions are 22x27x45 Lagoon
    40" in shallow end and 8' in deep end
    That IS a bigun. The only thing I can think of would be some possible dirt, algae or chemicals in the water giving you higher turbidity than normal. It can look crystal clear but have enough in it to skew the CYA test.

  8. #8
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    Default Re: CYA Level Somehow Increased

    What kind of chlorine are you using?

    If you are using trichlor pucks (which are stablized with CYA) and you added a bunch since its a new pool, they will send your CYA through the roof.

  9. #9
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    waterbear is offline Lifetime Member Sniggle Mechanic waterbear 4 stars waterbear 4 stars waterbear 4 stars waterbear 4 stars
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    Default Re: CYA Level Somehow Increased

    IF your CYA level was high before you drained it is possbile that some had depostited in your plumbing and had redissolved after you refilled. However, I don't think you would have had enough in the plumbing to raise your CYA an additional 60 ppm or so! I would suspect that there is some initial cloudiness in your water that is skewing the CYA tests, perhaps from a nascent algae bloom or perhaps some calcium carbonate precipitating out from high TA nd CH. The latter is entirely possible given your TA of 170 ppm and pH of 7.8!
    Retired pool store and commercial pool maintenance guy.

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