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Thread: Chlorine potency?

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    Chlorine potency?

    I have 12.5% chlorine that doesn't seem to be very strong.
    Could the fact that it is stored on my radiant concrete floor which is kept at 95 deg. have affected it and made it less strong?
    21,000 gal Fiberglass (Indoor)

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD
    Yes! Bleach loses potency over time. The higher the temperature and the higher the concentration the faster it decays. At 70 degrees 12.5% is only good for six to twelve weeks, at higher temperatures it will decay much more quickly.
    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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    Join Date
    Mar 2007
    San Rafael, CA USA
    The chart at the bottom of this link gives the half-life of chlorine at various concentrations and temperatures FOR HIGH QUALITY CHLORINE (lower quality chlorine will degrade faster). 12.5% chlorinating liquid at even 90F will have a half-life of around 70 days. At 75F, the half-life is around 220 days. Remember that these are half-lifes so the time it takes to lose half its potency and the loss will be faster early on as the concentration is higher. At 90F, the drop from 12.5% to 10.0% occurs in about 22 days -- again, for high-quality chlorine.

    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
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  4. Back To Top    #4
    Thanks all, for the info
    21,000 gal Fiberglass (Indoor)

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