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Thread: CYA Related Question

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    Join Date
    Jun 2013
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    Tampa, FL
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    CYA Related Question

    I haven't tested my CYA for a couple of weeks and to be completely honest it is the test I have the least amount of confidence in with my Taylor K-2006 kit. I haven't been overly concerned about testing my CYA as my Free Chlorine has been extremely stable and minor adjustments on my IC40 provide predictable changes. I feel very confident in my ability to maintain my chlorine level now. Early in the learning curve this wasn't so.

    Anyhow, today I decided to test all my "levels" just to see where everything was as:

    FC - 5.0
    CC - 0
    Ph - 7.5
    TA - 80
    CYA - ~20

    Yesterday, my FC was at 6.5 so I decided to drop it to 5 before setting my IC40 back @ 20%. 20% has been doing the trick for maintaining my chlorine level. Approximately 20hrs passed from when I turned the IC40 off to when I set it back to 20% (a drop from 6.5 to 5 in that window).

    So my question is:

    How concerned should I be about a CYA of ~20 if my chlorine appears stable? I have started addressing my apparent low CYA already but there is a small part of me that wonders if I should be?
    Approx 18,000gal outdoor pool (in-ground vinyl liner) with two large oak trees in the back yard which shade the pool late in the day (and make the pool a mess in the spring).

    Equipment:
    Pentair Intellliflo VS+SVRS, Pentair IC40, Pentair CCP 320 (Cartridge Filter), Polaris 9400sport (pool cleaning robot), Testing kit: Taylor K-2006

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
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    Re: CYA Related Question

    With a higher CYA, the SWG will not have to run as much to maintain the FC. And should extend they life of the cell.
    Jason, TFP Moderator
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    Re: CYA Related Question

    Quote Originally Posted by jblizzle
    With a higher CYA, the SWG will not have to run as much to maintain the FC. And should extend they life of the cell.
    I guess that is where I am a bit puzzled. I would have expected that with a low CYA to have my chlorine level be a little less stable. Is this an incorrect assumption? I have no trouble maintaining my chlorine levels with my SWG set at 20% (it can't be set lower), so wouldn't that mean (not considering maintenance and other variables) it would have the longest life expectancy possible?

    Thanks for the quick response.
    Approx 18,000gal outdoor pool (in-ground vinyl liner) with two large oak trees in the back yard which shade the pool late in the day (and make the pool a mess in the spring).

    Equipment:
    Pentair Intellliflo VS+SVRS, Pentair IC40, Pentair CCP 320 (Cartridge Filter), Polaris 9400sport (pool cleaning robot), Testing kit: Taylor K-2006

  4. Back To Top    #4
    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    37,879

    Re: CYA Related Question

    If your SWG is already set to the lowest percentage available, then you are correct that adjusting CYA will not increase cell lifetime (unless you reduce pump runtime).

    Lower CYA levels mean much more variation in your FC level, as sunlight will use it up fairly quickly, and a higher percentage will get used up any time a person gets into the pool. Chlorine levels from day to day could easily be very stable, but there has to be some variation from hour to hour, especially during periods when the pool is getting a lot of light.
    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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