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Thread: Why is CYA desired when using SWG in spa?

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    Why is CYA desired when using SWG in spa?

    Why not just up the setting on SWG to compensate for greater fc loss?
    650 gal Thermospa Aquacisor, well water with half softened water

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    Mod Squad jblizzle's Avatar
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    Re: Why is CYA desired when using SWG in spa?

    Because the CYA also acts as a buffer so the chlorine is not as harsh on you and the equipment. Same reason we recommend it for indoor pools as well.
    Jason, TFP Moderator
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    pwrstrk's Avatar
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    Re: Why is CYA desired when using SWG in spa?

    Take a look at this from chemgeek.
    Cyanuric Acid (CYA) is not just for protecting chlorine from breakdown from sunlight, but also significantly moderates chlorine's strength. 4 ppm Free Chlorine (FC) with 30 ppm CYA in a hot (104ºF) tub is roughly equivalent to around 0.6 ppm FC with no CYA. If you don't use any CYA, then the chlorine is too strong and will react more quickly with swimsuits, skin, hair, as well as outgas faster and oxidize hot tub covers more quickly and yes, this increases chlorine demand. You want some CYA in the water to act as an active chlorine (hypochlorous acid) buffer so you have plenty in reserve while keeping its strength to reasonable levels. With no CYA, the chlorine is too strong (unless you try and maintain very low chlorine levels, but that is generally hard to do) while with too much CYA the chlorine is too weak and takes too long to oxidize bather waste and can be too weak to kill some pathogens.
    Jeff
    24'x54" AG Morada RTR (by wilbar) 13'500 gal. Hayward Powerflo Matrix 1hp 2 speed. Hayward Perflex EC65 DE filter.

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    Re: Why is CYA desired when using SWG in spa?

    I see. So SWG is irrelevant here? (Don't currently have one).

    But I'm currently running an ozonator.

    Does it alter the oxidation factor? (Maybe less CYA required).

    Also, what is effect of oxidizing the cover? Does the bottom vinyl go bad before the top?
    650 gal Thermospa Aquacisor, well water with half softened water

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    Re: Why is CYA desired when using SWG in spa?

    I know you guys have established good practices. I've run my tub for 1.5 seasons now, and have just started to get serious with doing it right (just got in my Taylor K-2006).

    Todays #s:


    TA 40
    PH 7.4
    FC 2.4
    CC .2
    SA .43

    no CYA

    guess it's time to get some...
    650 gal Thermospa Aquacisor, well water with half softened water

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