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Thread: CYA/FC relationship

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    CYA/FC relationship


    New pool owner in a week. Took back the Frog System and decided to go with BBB. Thanks for all of the info.

    My question is this--If CYA stabilizes the Chlorine, why is more needed as more CYA is in the pool? Meaning--why does that chlorine become "unavailable" (my translation--as more CYA=more Cholrine needed to maintain)? And if it is unavailable, what good is it?

    Hope this makes sense.

    24' AG Doughboy w/ 5'8 dish bottom, CWII DE Filter, 1.5 hayward 2 speed pump, Aquatrol SWG.

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    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana

    Re: CYA/FC relationship

    At any given CYA level, a percentage of the chlorine in the pool is bound to the CYA and a percentage is unbound or "active". The chlorine bound to the CYA is not actively sanitizing the pool, but it is made available for sanitation as the active portion of the chlorine is consumed. At higher CYA levels, a larger percentage of the chlorine remains bound, so the amount of "active" chlorine is lower than it is at more reasonable CYA levels.

    The chlorine bound to the CYA is "on the bench", while the rest is in the game, so to speak. Higher CYA means more players on the bench and fewer in the game.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: CYA/FC relationship

    Thanks for an analogy I can understand. So when the FC is measured, that figure is also measuring the chlorine that is bound to the CYA, hence the great FC numbers need in relation to CYA. Correct?
    24' AG Doughboy w/ 5'8 dish bottom, CWII DE Filter, 1.5 hayward 2 speed pump, Aquatrol SWG.

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    dmanb2b's Avatar
    Join Date
    Apr 2009

    Re: CYA/FC relationship

    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

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