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Thread: When does Chlorine level return to normal

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    Join Date
    Jun 2011
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    Montgomery, AL
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    When does Chlorine level return to normal

    I shocked my pool last night after a large pool load and rainstorm. I brought the level up to 20 and am now wondering how long before the FC is at a level where swimmers can re-enter. It's Friday and the weekend is coming with hot days. What would be a good guess about normal FC level?
    33,000 (20x40 3-8 ft), Hayward Sand Filter, vinyl, 1HP pump, Dolphin Deluxe 3

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    In the Industry


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    Re: When does Chlorine level return to normal

    A few things:

    shocking the pool is a process that often takes several days
    normal (recommended) FC levels are 3-7ppm (but will vary based on CYA)
    swimming at shock levels will be fine (so you are all set for the weekend)
    FC retention will be affected by CYA level, direct sunlight, and bather load

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    Richard320's Avatar
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    Re: When does Chlorine level return to normal

    Did you really shock? That's a process, not a one-time blast of chlorine.

    I'm afraid the answer depends upon your CYA level. If it's 50 or above, you can go in right now. I'd suspect it will only take a couple hours to come down if you had a big load.

    Just break out the test kit, see what CYA is and what FC is and compare it to this chart. If FC is below shock level for your CYA you're good to go.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: When does Chlorine level return to normal

    CYA is 40 and the target shock is 16, but I brought it up a bit higher just to be safe. The OCT held and it is coming down just trying to see how long. So they can swim at a level of 15? I suppose it will jut fade their suits a little and dry skin or no? I'll tell them it's okay. Thanks.

    I think I'm going to bring my FC up above target level for a bit because we are supposed to get thunderstorms and heavy rain for the next week to week and a half.
    33,000 (20x40 3-8 ft), Hayward Sand Filter, vinyl, 1HP pump, Dolphin Deluxe 3

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    Re: When does Chlorine level return to normal

    I always add chlorine based on a guesstimate as to what tomorrow's weather will bring. The sun burns up much more chlorine than rain dilutes it.

    Above normal usage I don't anticipate more than 1-1.5ppm during a storm.


    Also - with the heat we've been having your FC levels might be low enough to swim by now.
    Aaron
    [ Vogue Vectra 24' AG | Hard plumb: Hayward Power-Flo Matrix 1HP 2-speed, 27" sand filter & Pentair MiniMax 100 NG | Taylor K-2006 | Central IL ]
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