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Thread: Normal chlorine consumption rate

  1. Back To Top    #1

    Join Date
    Sep 2010
    Location
    Tampa, FL
    Posts
    14

    Normal chlorine consumption rate

    I finally broke down last week and bought a test kit that allows you to test chlorine levels above 5ppm. After being told by the pool store guys for over a year that my CYA was 100 ("That's as high as we can test for but it's ok since you live in Florida" or my favorite "Take the pucks out for a week and the CYA will evaporate") and that my FC was 5ppm ("too high," odd given aforementioned CYA level), I'm now able to accurately see what is really going on in my pool.

    My CYA is 60, and it turns out I've been maintaining a FC level somewhere between 12-15ppm from all the weekly shocking.

    Thanks to this site I've been able to ditch the pucks, and my water looks and feels a hundred times better.

    Is there a rule of thumb for how much chlorine a pool should use on a daily basis? Depending on which CYA/Chlorine chart I use, given a CYA of 60, minimum FC is 4.5-5.0ppm and target FC is 8ppm. I usually raise it up to about 8.5 at night, measure it at 7.0-7.5 the next morning and it's back uncomfortably close to 4.0-5.0 by evening.

    Is this a pretty typical consumption rate? The pool is used every day and gets about 6 hrs of direct Florida sun.

    Most recent measurements...

    FC 5.0
    CC 0.5
    TC 5.5
    CYA 60
    PH 7.5
    CH 260
    TA 70

    Thanks!

    Doji
    15,000 gallon outdoor in-ground plaster pool
    Sand filter flow rate 62 GPM
    3/4hp pump

  2. Back To Top    #2

    Join Date
    Jun 2010
    Location
    Glendale, CA
    Posts
    513

    Re: Normal chlorine consumption rate

    Every pool is going to be different but somewhere between 1 and 3ppm a day loss seems typical. The higher you run you FC above your target value the more you loose to the sun.
    16K Gal Plaster | Compupool SWG | Intelliflow VF | TF-100

  3. Back To Top    #3

    Join Date
    Sep 2010
    Location
    Tampa, FL
    Posts
    14

    Re: Normal chlorine consumption rate

    Quote Originally Posted by lightingguy
    The higher you run you FC above your target value the more you loose to the sun.

    Trying to wrap my brain around this. So the lower my FC is the less I will lose to the sun?

    So if 8ppm is my target and 5ppm is my minimum, the closer it gets to 5ppm the less will be consumed?

    Thanks!

    Doji
    15,000 gallon outdoor in-ground plaster pool
    Sand filter flow rate 62 GPM
    3/4hp pump

  4. Back To Top    #4

    Join Date
    Mar 2007
    Location
    Coastalish 'down easter'
    Posts
    4,160

    Re: Normal chlorine consumption rate

    Welcome to TFP!!

    The chlorine 'demand' depends on a few things - Sun eats it up very quickly, without adequate CYA, the number of folks using the pool (more bathers= more chlorine needed) and organic debris entering the pool (i.e. you always have leaves or grass clippings blowing into the pool) will use up your chlorine.

    The use and amount of debris blowing in varies from pool to pool so, it's hard to say how 'normal' your consumption is - what I'd do is keep track of how much chlorine you're using vs. bather load and need to vacuum, manually skim and amount of stuff in the skimmer basket(s). This should give you a 'baseline' from which you will know that after a pool party or a storm, you'll need to add extra chlorine and probably a good idea of how much extra chlorine you'll need to add

    Your pool is unique and you can learn how it responds to different situations - as you become more experienced with it, you'll know what the tests are gonna show you before you add the last drop
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

  5. Back To Top    #5

    Join Date
    Jun 2010
    Location
    Glendale, CA
    Posts
    513

    Re: Normal chlorine consumption rate

    Sorry - didn;t mean to confuse.

    If your range is 5ppm to 8ppm - 5ppm is the minimum you want to have enough active agent in the water and 8ppm is the high end where the sun starts to get at it more aggressively. Low balling the range is much more trouble than it is worth - though in theory you might shave a few tenths of a PPM per day off your loss.

    I only mentioned it because you noted running a higher FC level (15ppm or so). At those elevated levels loss to sunlight will be more extreme.
    16K Gal Plaster | Compupool SWG | Intelliflow VF | TF-100

  6. Back To Top    #6

    Join Date
    Sep 2010
    Location
    Tampa, FL
    Posts
    14

    Re: Normal chlorine consumption rate

    Quote Originally Posted by lightingguy
    Sorry - didn;t mean to confuse.

    If your range is 5ppm to 8ppm - 5ppm is the minimum you want to have enough active agent in the water and 8ppm is the high end where the sun starts to get at it more aggressively. Low balling the range is much more trouble than it is worth - though in theory you might shave a few tenths of a PPM per day off your loss.

    I only mentioned it because you noted running a higher FC level (15ppm or so). At those elevated levels loss to sunlight will be more extreme.

    Thanks for the clarification. The only reason I'd been at 15ppm is ignorance and my reliance on the pool store.
    15,000 gallon outdoor in-ground plaster pool
    Sand filter flow rate 62 GPM
    3/4hp pump

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