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Thread: Advice on Daily Chlorine adjustment for sun

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    Advice on Daily Chlorine adjustment for sun


    FC 7
    CC .5
    CYA 60
    PH 7.5

    I need some advice on how to adjust for the daily consumption of CL by the sun. Oklahoma City. Hot and sunny.

    the cya/cl chart gives me a minimum of 5 and a FC target of 7 for a CYA of 60.

    I am losing anywhere between 5-10 ppm of CL each day due to sun, I pass OTCL.

    If I assume I will have 8 ppm loss due to sun each day, should I add that on top of the 5 or the 7, and when should I add that CL, at night or in the morning.

    I will probably raise my cya to 70. But even if I do, I may have sun loss that requires a daily dose above the target, and I am not sure how to calculate that.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Advice on Daily Chlorine adjustment for sun

    If you are losing that much chlorine to sunlight, you are either raising your morning FC level too high (FC loss is proportional to your starting FC level), CYA isn't really at 60, or you have algae. Even with extreme amounts of sunlight, you shouldn't lose much more than 50% of your starting FC level, given CYA around 60.

    The correct way to find the evening target level is to note the level the next evening. If FC is too low the next evening, raise your FC target level. If FC is too high the next day, lower your target.
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