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Thread: Question about the Chlorine/CYA ratio

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    stev32k's Avatar
    Join Date
    Mar 2009
    Mobile, Alabama

    Question about the Chlorine/CYA ratio

    I don't understand the chemistry of the chlorine/CYA ratio, but wonder if there is any reason to maintain a higher or lower CYA concentration. Is there any advantage to maintaining say 40 ppm CYA over a 20 ppm concentration? The lower CYA number would require a lower chlorine number which would let my liquidator go longer between refilling and use less chlorine. I've been keeping the CYA at 40 ppm but not really sure if there is any good reason why it should be 40 instead of 20.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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

    Re: Question about the Chlorine/CYA ratio

    You would probably use more chlorine at 20ppm. At 20ppm, you will probably struggle to keep your pool chlorinated in the middle of the day. The sun will destroy it faster than you add it, which can let your FC level get down to zero. Raising it to around 40ppm is a good compromise between protecting your chlorine while still allowing you to have a reasonable shock level if you need it.
    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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    Isaac-1's Avatar
    Join Date
    May 2010
    SW Louisiana

    Re: Question about the Chlorine/CYA ratio

    In other words a lot of it is about sun exposure, this means your optimal CYA level with a typical mid North America location with some shading will likely be around 40 ppm, with full sun you will likely want around 50 ppm, and prime sun belt location like south Florida may want even higher.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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