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Thread: Chlorine consumption per bather

  1. Back To Top    #1
    Daf-Tekno's Avatar
    Join Date
    Sep 2014
    Calgary / AB

    Chlorine consumption per bather

    Hi TFP,

    I'm sure I read this in another thread somewhere, but for the life of me I can't find it!
    And searching doesn't seem to give any usable results.

    Can anyone tell me how much chlorine 1 bather consumes in a spa over a given time period?
    (Jacuzzi Calgary told me 1 person uses 1 ppm every 15 minutes, though it's been a long time since I trusted anything they've said...)

    Thanks - D
    Jacuzzi J480 (2008) 1700 litres, Balboa ozonator, Delta EZ-18-120 UV lamp via custom 6-way 2-tier timer solenoid array, 2 x Waterway 4HP main pumps,
    1 x Aqua-Flow 1/15 HP circ pump, ChlorMaker IL SWG, SmartSeal + Roxul skirting insulation, 8' x 8' ThermoFloat Spa blanket, 100" x 100" Gator coverall

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Chlorine consumption per bather

    The rule of thumb I have heard is 5 fluid oz of 6% bleach (or the equivalent) per person/hour. Actual usage varies somewhat depending on many factors, this is just a typical/average number.

    You don't measure in ppm, because chlorine usage per person/hour is an absolute amount, while 1 ppm varies with the tub size.
    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

  3. Back To Top    #3

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Chlorine consumption per bather

    For a hot (104F) spa it's roughly 9 grams of chlorine (in weight Cl2) per person-hour which translates to 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 3-1/2 fluid ounces of 8.25% bleach or 7 teaspoons of non-chlorine shock (43% MPS -- a disinfectant only with silver ions as with Nature2). In 350 gallons, which is a typical spa size, this is 6.8 ppm FC so every 15 minutes that would be 1.7 ppm FC. So the rule of thumb you were given was either for a larger 600 gallon spa or they somewhat under-estimated.

    It's a rule-of-thumb anyway and depends on the cleanliness of the bather, their size, how much they usually sweat, water temperature, etc. The real rule you should use is to add whatever amount of chlorine is necessary after a soak so that you still measure at least a small residual of chlorine for the start of your next soak. You should never let the chlorine level get to zero (or near-zero), certainly not for more than an hour or so.
    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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