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Thread: How long till chlorine drops?

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    How long till chlorine drops?

    O.K. I had to shock for the first time. I had a very light algae or something.

    Once I'm done, how long till the chlorine drops to swimmable levels? I shocked to 24 TC, vinyl 24,000 gallon pool. Temp now about 85, outside temps 100. Lots of direct sun.

    Any guesstimates? And what is a safe tc for swimming, 7 I think?
    18' x 36' saltwater inground vinyl pool

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    Re: How long till chlorine drops?

    After shocking a friends pool, we saw FC drop 50% in one day at CYA 30. Drop would be far less at higher CYA levels.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    frogabog's Avatar
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    Re: How long till chlorine drops?

    Really though... isn't it ok to swim at shock levels if it's shocked appropriately for CYA? I do remember reading this last summer here on the forums. It isn't gonna kill you and might even assist anyone with athlete's foot who goes swimming :~}
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
    Year 3 BBB -15' x 48" Intex Metal Frame - Was using (2) 1000gph Intex cartridge filters (see Full time pumping Intex). 2012, converted to 1600gph and sand filter+SWG = Sand filter love affair!
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    Re: How long till chlorine drops?

    We got in that pool at something a bit below shock level and while the day before it fell by 50% in 11hours, when we swam, it fell 25% in 4 hours, so a bit faster than it did with just sunlight.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

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    Butterfly's Avatar
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    Re: How long till chlorine drops?

    Most of us say it is okay to swim with FC above min and below shock level for your CYA level.
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    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    JasonLion's Avatar
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    Re: How long till chlorine drops?

    ouachita, it is impossible to guess how long without knowing your CYA level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: How long till chlorine drops?

    Sorry Jason, CYA is 30. I went by the pool calculator and shocked according to Mustard Algae levels just in case. I know the CYA is low. I'm gonna work on that as soon as the shock is over. By the way, standard shock was listed at about 15. Don't quote me on that. I just went ahead and went to the Mustard Algae level, which I don't think I had.

    You know, July 4th weekend coming up. Gotta use the pool.

    And by the way, I meant FC and not TC on my shock levels. When I started the shock I had.5 FC and .5 to 1 CC. It was hard to tell. Need to order a new test kit! The cylinder is getting old.
    18' x 36' saltwater inground vinyl pool

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    maxepr1's Avatar
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    Re: How long till chlorine drops?

    Turn your SWG off first, shouldn't take too long 3-4 days maybe. I wouldn't see a reason why you couldn't swim on the 4th. Took almost 10 days for me but my CYA was higher than yours.
    40'x19' IG Diamond Brite 29K 4' Waterfall/Dive Rock FNS60 DE Inteliflo VS 2hp Whisperflo pumps Aqualogic(P4) SWG TF100 Tester


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    JasonLion's Avatar
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    Re: How long till chlorine drops?

    With CYA at 30, the FC level will be done to the high side of normal by tomorrow evening, if not before.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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