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Thread: Chlorine consumption

  1. Back To Top    #1

    Chlorine consumption

    Hey all,

    Haven't been around for a while - things have been GREAT. We still love the tub and thanks to you all it has been very low maintenance.

    Current #'s

    FC - 8.5
    CC - <1
    pH - 7.6
    TA - 50
    CH - 130

    Assumed other values from prior test or in the case of Borates just educated guess from Poolcalc:

    Borates - 50
    CYA - 45

    - Water changed on 5/31
    - Ozonator disabled 7/29

    Over the last few weeks the tub has been consuming larger and larger quantities of chlorine. This morning the tub was at ~4FC so I added 8oz of 6% which should have brought it up to shock levels @ around 17. When I get home about 10 hours later it is down to 8.5FC. Similar cycles over the last few weeks, with larger and larger doses of choline.

    I'm working on the assumption that at some point it got too low for too long and caught a bug. Probably while we were out of town and it was being cared for by a friend.

    Unless you guys/gals tell me otherwise, my intent is to keep bringing it up to shock levels 1 or 2 times/day until it slows down consumption?

    Also I was wondering, if I don't use of of the jets/features/waterfalls etc, it seems there would be stagnant water in those lines. Is that a problem? If so, how often do I need to run/flush them to prevent problems developing there?

    Any other advice?

    Thanks all.......

    -Chak
    290 Gallon fiberglass reinforced acrylic spa
    Cartridge filter
    Above Ground
    2 x 5HP pumps - unknown flow rate.
    Ozonator
    --------------------------------------------
    6800 Gallon 17' x 48" Vinyl above ground pool (Summer Escapes)
    Intex 2650 Sand Filter

  2. Back To Top    #2

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Chlorine consumption

    Yes, it sounds like the oxidizer level was too low for the demand at some point and you are now behind and need to get caught up. Shocking at higher chlorine levels will help you catch up (hopefully). Let us know how it works out.
    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"

  3. Back To Top    #3

    Re: Chlorine consumption

    Ok, so now a couple of weeks into this. Consumption is still high. Last night I raised the tub to ~14FC and today it is down to 8.5.

    I haven't been 100% diligent but have been enough where it has never gotten below 6FC and even then only once or twice since the original post.

    The spa is clear and seems happy - no other symptoms.

    With the water being 3 months old perhaps I should just change it this weekend? Does older water just consume more? I wouldn't think so.....

    -Chak
    290 Gallon fiberglass reinforced acrylic spa
    Cartridge filter
    Above Ground
    2 x 5HP pumps - unknown flow rate.
    Ozonator
    --------------------------------------------
    6800 Gallon 17' x 48" Vinyl above ground pool (Summer Escapes)
    Intex 2650 Sand Filter

  4. Back To Top    #4

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085

    Re: Chlorine consumption

    Chak,

    Well, it does seem like you've got something consuming chlorine a bit more than usual though 14 to 8.5 is a loss of around 40% -- higher than the 25% one usually sees initially but not as high as the 50% level where there's more cause for something going on.

    You can always change the water anytime you want. If you suspect that there's something in the tub giving you higher chlorine demand, you can superchlorinate and/or use a product like Spa System Flush to thoroughly clean out the tub.

    The standard Water Replacement Interval (WRI) formula in days is (1/3) x (Spa Size in Gallons) / (# of bathers)
    where the presumed soak time is around 20 minutes. If you have one person soak for 40 minutes or two people soaking for 20 minutes then that would be a WRI of 48 days. With the Dichlor-then-bleach method one can usually go around twice as long a this so around 96 days which is about the 3 months you've gone. So maybe it is indeed time to change the water though I don't know how many people are soaking for how long every day in your tub.

    Richard
    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"

  5. Back To Top    #5

    Re: Chlorine consumption

    I think things are improving. Last night I brought it up to ~17FC. Tonight it was somewhere between 11 and 12 (reagent ran out during test and while it turned I don't think drop sizes were right).

    As far as usage, I started out tracking usage but that has fallen off. Early on we used it daily for around 1 man hour/day. Lately due to busy time and high heat we are down to a couple of man hours per week. When we use it I typically add 3oz/manhour of 6% to compensate. While we are generally clean people who work in offices during the day - we don't shower before tub time so we know more chlorine is needed.

    So to answer you question, I don't know how much we have used the tub. As someone unlikely to track things like that it is probably just best for me to change the water on a more aggressive schedule that might be called for

    I think thanks to all of you that I will continue boosting chlorine to shock levels until I get the consumption down to around 20%. Then, well, may let the level drop down to the 10FC range at peaks and maintain from there.

    All in all, thanks all - I love this site!!
    290 Gallon fiberglass reinforced acrylic spa
    Cartridge filter
    Above Ground
    2 x 5HP pumps - unknown flow rate.
    Ozonator
    --------------------------------------------
    6800 Gallon 17' x 48" Vinyl above ground pool (Summer Escapes)
    Intex 2650 Sand Filter

  6. Back To Top    #6
    spishex's Avatar
    Join Date
    Oct 2008
    Location
    Hillsborough, NC
    Posts
    1,375

    Re: Chlorine consumption

    How's your filter doing? Could be that you have some larger organic material hanging out in there.

  7. Back To Top    #7

    Re: Chlorine consumption

    Good call spishex - but I do clean it once a week when used heavily and every other week when being used lightly like right now.

    All that said, it seems that keep it up around PoolCalc's shock level for a while a greatly decreased consumption. When not used, in a 24 hour period is eats about 3 oz now - MUCH better.

    I now think that when it was being used for the 1 man/hour/day I was not adding enough to compensate for the fact we typically don't shower before we get in.

    Anyway, thanks for the help all - TFP has made this SOOO much better than what the spa guy told me to do!

    -Chak
    290 Gallon fiberglass reinforced acrylic spa
    Cartridge filter
    Above Ground
    2 x 5HP pumps - unknown flow rate.
    Ozonator
    --------------------------------------------
    6800 Gallon 17' x 48" Vinyl above ground pool (Summer Escapes)
    Intex 2650 Sand Filter

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