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Thread: CYA level advice needed

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    CYA level advice needed

    I have an outdoor above ground style vinyl pool located inside of a greenhouse structure. The greenhouse roof is 6 mil poly with UV stabilizer in it. The ends are screened with black nylon window screen, the ease end very treed and the west end near the house. This results in very little direct sunlight ever actually reaching the pool.

    Under normal conditions the chlorine level changes very slowly. You can be out all day and not need sunscreen.

    Under these conditions is CYA actually needed? If so, what level should I shoot for?


  2. Back To Top    #2

    Join Date
    Feb 2008
    Flower Mound, TX

    Re: CYA level advice needed

    Around these parts, we typically recommend at least 20 ppm of CYA for indoor or close to indoor pools.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
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  3. Back To Top    #3
    Melt In The Sun's Avatar
    Join Date
    Oct 2009
    Tucson, AZ

    Re: CYA level advice needed

    I think you can treat it as an indoor pool, and keep CYA at 20 or 30. You want some CYA in the water to "mellow out" the effect of the chlorine (so you don't bleach your swimsuits too fast).

    257 beat me to it...
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
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  4. Back To Top    #4

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: CYA level advice needed

    If there is minimal UV reaching the pool, then I'd target 4 ppm FC with 20 ppm CYA. The higher FC boosts the active chlorine level to partially make up for the lack of UV. Some components of sweat and urine are slow to oxidize and need a higher active chlorine level unless there is UV to help break them down. In some cases, you may find you need supplemental oxidation -- some indoor pools use UV systems if they find trouble keeping Combined Chlorine (CC) low.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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