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Thread: Shelf Life of Sodium Hypochlorite

  1. Back To Top    #1

    Join Date
    Apr 2008

    Shelf Life of Sodium Hypochlorite

    I was thinking of stocking up on bleach for next year and came across this study on the shelf life of sodium hypochlorite

    Looks like it loses about 50% of its strength in about 1 year from production. Link also examines different storage conditions.

    For what its worth.
    18'6" x 36'6" Grecian In-ground
    27,000 gal. (give or take)
    Sand Filter
    Solar Cover

  2. Back To Top    #2

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Shelf Life of Sodium Hypochlorite

    A more complete table is shown at the bottom of this link where you can see that roughly speaking the half-life of product varies as the square of the concentration, such that 6% bleach lasts about 4 times longer than 12.5% chlorinating liquid, all else equal. You can also see that the half-life is roughly cut in half (product lasts half as long) with every 10F increase in temperature.

    The actual rate of loss is also very dependent on the purity of the product which may account for the seemingly small differences vs. temperature in the link you gave. In my experience, the link I give above is reasonably accurate, at least for 12.5% chlorinating liquid which is what I use.

    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"

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