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Thread: Need help with CYA

  1. Back To Top    #1

    Join Date
    Jun 2010
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    Toronto, ON. Canada
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    Need help with CYA

    About 2 weeks ago, our CYA was at 30. I added 1.8Kg of stabilizer (from Walmart) and according to the calculator it should have brought it up by 27.

    Tested today and CYA is at 40. I had a similar problem last year where I would add stabilizer as per the calc but it never got to what I would think it would. No backwash done.

    Why would this be?

    Aside from losing stab when a pool is drained, how else would one lose it?
    16'x34' Inground Vinyl Pool. 65,500L. Hayward S244T2 24 Sand Filter. Hayward 1hp Super Pump. Raypak PR266 EN 266,000 btu,. AquaRite SWCG. Aqualamp LED 2 w/ remote

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    zimm's Avatar
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    Re: Need help with CYA

    Maybe your capacity calculation is off on the pool? Have you added any chlorine manually (besides your SWG)?
    45'x12' 17k gal, IG plaster, Pool Pilot Nano+ SWG, 1/2hp Whisperflo pump, PAC-FAB TA-60D sand filter, Raypak 266 heater
    Pool School + Test Kit + Pool Math = Trouble Free Pool

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    northrn's Avatar
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    Re: Need help with CYA

    Evidently, I have reading comprehension problems today....never mind me.

    27' AG 18K Gallons ~ Cartridge Filter ~ Pentair 1.5 HP Pump

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    Re: Need help with CYA

    Quote Originally Posted by Shaf77 View Post
    About 2 weeks ago, our CYA was at 30. I added 1.8Kg of stabilizer (from Walmart) and according to the calculator it should have brought it up by 27.

    Tested today and CYA is at 40. I had a similar problem last year where I would add stabilizer as per the calc but it never got to what I would think it would. No backwash done.

    Why would this be?

    Aside from losing stab when a pool is drained, how else would one lose it?
    I have added chlorine and that usually measures out fine...
    16'x34' Inground Vinyl Pool. 65,500L. Hayward S244T2 24 Sand Filter. Hayward 1hp Super Pump. Raypak PR266 EN 266,000 btu,. AquaRite SWCG. Aqualamp LED 2 w/ remote

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    ship of fools's Avatar
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    Nov 2011
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    Albany, NY
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    Re: Need help with CYA

    My pool is 16 x 32 with a deep end. I have mine calculated at 21,000 gallons. If the conversion on the internet is accurate 65,500 is 17,000 gallons+- so maybe you are more than 65,500 liters??
    21,000 gallon inground
    Haywood Sand Filter
    Vinyl Liner

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    Toronto, ON. Canada
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    Re: Need help with CYA

    Here is the sizing and volume from the manufacturer...

    17,300 US Gallons
    14,500 Imp Gallons
    65,500 Litres

    16'x34' Inground Vinyl Pool. 65,500L. Hayward S244T2 24 Sand Filter. Hayward 1hp Super Pump. Raypak PR266 EN 266,000 btu,. AquaRite SWCG. Aqualamp LED 2 w/ remote

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    Donldson's Avatar
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    Re: Need help with CYA

    Because the CYA test is the most subjective and has the largest margin of error of all the tests it us quite pissible this was just a testing error. If your CYA was a bit lower than measured when you started and a bit higher than it measures now that would explain it.

    The current CYA test is the most accurate available at a consumer level, even if very imperfect. Since the FAS-DPD is far more accurate, and your chlorine does what you calculate it should, then your pool size is likely correct. So treat your CYA as it reads and add more if you want it higher.

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