Become a TFP Supporter Welcome to our new server and new forum software. Pool School
Results 1 to 11 of 11

Thread: Does liquid chlorine go bad?

  1. #1
    Senior Member Lana537's Avatar
    Join Date
    May 2009
    Location
    The Triangle, NC
    Posts
    238

    Does liquid chlorine go bad?

    Hi Everybody~~

    DH just told me that our 12% liquid chlorine will go bad--that it has a finite shelf life.

    We keep 3 or 4 jugs of this around, stored outside, just in case of a power failure or whatever. Now he tells me that it is not like Clorox. It has a shorter life.

    He says that bleach is better--it is 6% -ish and is more stable, and therefore it lasts longer on the shelf, but the fact is that we like to be able to buy something from our neighborhood pool store occasionally to keep up a little patronage/relationship going, so we buy some of the liquid chlorine....

    Yes, I am lazy, and I have not searched our site for other postings on this; it's been a long day in an already too-long week.

    Any quick short comments? Thank you very much!

    Weary Lana
    25,000 gallon, refurbished 1960's inground concrete, Jandy sand filter w Jandy 1.5hp single-speed pump, Pool Pilot Digital SWCG+Chemtrol 2100+CO2 tank; PebbleTec White Pearl with 10% Cobalt Blue Dark Beadcrete by Olympic Pool Plastering, Georgia. Taylor K-2006 Test Kit; Aqua Check Salt test; LaMotte borates test, and Jack's Magic Sequest test kit; SparklyPoolitis level: extremely high.

  2. #2
    Member
    Join Date
    Sep 2010
    Posts
    81

    Re: Does liquid chlorine go bad?

    Yes, it will degrade over time. The same goes with 6% as well.
    1971 San Juan Fiberglass pool 12,000 gallons
    New Pentair Whisperflow 1hp
    New Pentair FNS DE filter 64sq
    All 1.5" piping and no heater
    1 skimmer, 1 main drain, and 2 returns

  3. #3
    Senior Member
    Join Date
    Feb 2008
    Location
    Flower Mound, TX
    Posts
    5,169

    Re: Does liquid chlorine go bad?

    Typically, the higher the initial concentration of sodium hypochlorite, the faster it will degreade. So...12% loses strength quicker than 6%, and so on. How it is stored plays a large part in this too. Higher temperatures speed the degradation process.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
    TF Test Kits - Pool Math - Pool School
    "It depends."- JohnT

  4. #4
    Senior Member Lana537's Avatar
    Join Date
    May 2009
    Location
    The Triangle, NC
    Posts
    238

    Re: Does liquid chlorine go bad?

    Good grief!

    So when I buy this 12% chlorine, or Clorox bleach at some store with bad stock rotation, I have no idea how fresh or how old it is. Darn!

    Lana
    25,000 gallon, refurbished 1960's inground concrete, Jandy sand filter w Jandy 1.5hp single-speed pump, Pool Pilot Digital SWCG+Chemtrol 2100+CO2 tank; PebbleTec White Pearl with 10% Cobalt Blue Dark Beadcrete by Olympic Pool Plastering, Georgia. Taylor K-2006 Test Kit; Aqua Check Salt test; LaMotte borates test, and Jack's Magic Sequest test kit; SparklyPoolitis level: extremely high.

  5. #5
    Senior Member Lana537's Avatar
    Join Date
    May 2009
    Location
    The Triangle, NC
    Posts
    238

    Re: Does liquid chlorine go bad?

    So lastly,

    What should I do with 4 jugs of 12% chlorine that I have had sitting outside in the glorious North Carolina summer? I guess I will bring it in for the winter and consider it compromised yet not a total waste.

    In the future, I think I will keep indoors future purchases of Clorox, downstairs in the cooler guest room amidst the fresh towels and fancy guest soaps. (again, fatigue affecting my strange sense of humor)

    Thanks everybody. No matter how much I learn here, a lot can slip by. All the more reason to stay active and tuned-in to what is on the forum.

    Thank you!

    Lana
    25,000 gallon, refurbished 1960's inground concrete, Jandy sand filter w Jandy 1.5hp single-speed pump, Pool Pilot Digital SWCG+Chemtrol 2100+CO2 tank; PebbleTec White Pearl with 10% Cobalt Blue Dark Beadcrete by Olympic Pool Plastering, Georgia. Taylor K-2006 Test Kit; Aqua Check Salt test; LaMotte borates test, and Jack's Magic Sequest test kit; SparklyPoolitis level: extremely high.

  6. #6
    Senior Member
    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    9,183

    Re: Does liquid chlorine go bad?

    Though the half-life of chlorine depends a lot on its quality (since any metals in the water will much more quickly degrade the chlorine), the chart at the bottom of this page shows the half-life of chlorine at various concentrations and temperatures. Roughly speaking, 12.5% chlorinating liquid has a half-life (will get to 6.25%) of around 75 days at 90ºF, 106 days at 85ºF, 156 days at 80ºF, and 231 days at 75ºF. So you can see that it is very dependent on temperature (which is over both day and night).

    6% bleach will last around 3-4 times longer with a half-life (will get to 3%) of around 294 days at 90ºF, 420 days at 85ºF, 617 days at 80ºF and 914 days at 75ºF.

    So if you store your bleach at room temperature, it can last for many months if not years, though there will be some degradation. I know we have some very old Clorox Regular bleach in our laundry room that is still very potent. Chlorinating liquid left outside, especially if heated by the sun, will degrade much more quickly. You generally want to use it within a month or two and certainly can't keep it for an entire season unless you kept it artificially cool.
    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"

  7. #7
    Senior Member Lana537's Avatar
    Join Date
    May 2009
    Location
    The Triangle, NC
    Posts
    238

    Re: Does liquid chlorine go bad?

    Once again, thank you for your help, links, and information! I very much appreciate it.

    Lana
    25,000 gallon, refurbished 1960's inground concrete, Jandy sand filter w Jandy 1.5hp single-speed pump, Pool Pilot Digital SWCG+Chemtrol 2100+CO2 tank; PebbleTec White Pearl with 10% Cobalt Blue Dark Beadcrete by Olympic Pool Plastering, Georgia. Taylor K-2006 Test Kit; Aqua Check Salt test; LaMotte borates test, and Jack's Magic Sequest test kit; SparklyPoolitis level: extremely high.

  8. #8
    Senior Member X-PertPool's Avatar
    Join Date
    Jun 2009
    Location
    Exeter, PA
    Posts
    1,356

    Re: Does liquid chlorine go bad?

    Perfect idea. Buy your bleach in bulk then freeze it in ice cube trays for long term storage then when pool season hits you can just toss the little bleach pops right in the water for easy chlorination! lol
    -Kevin
    X-Pert Pool Service
    x-pertpool.com
    X-Pert Pool on Facebook and @XPertPoolServic on Twitter
    22,000 gal / 16' x 32' / Vinyl / Hayward s244t /Pentair SuperFlo 1 hp

  9. #9
    Senior Member
    Join Date
    Nov 2008
    Posts
    2,598

    Re: Does liquid chlorine go bad?

    I keep cal-hypo on hand for emergencies. I buy it in the biggest buckets I can handle and it will keep a long, long time.

    Like you, storing bleach is an issue when it gets hot outside. Not a problem in fall, winter, or spring, but summers at 100 degrees is hard on bleach. Was it stored in a hot warehouse before I got it? Just how hot is it in that shed outside in the sun? The garage was at 100 degrees, shed could be hotter.

    I am planning to try to switch to cal-hypo and pucks when possible in the heat of the summer, jumping back to bleach in fall.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

  10. #10
    Senior Member
    Join Date
    Jan 2009
    Location
    Cupertino, CA
    Posts
    1,974

    Re: Does liquid chlorine go bad?

    Quote Originally Posted by anonapersona
    Like you, storing bleach is an issue when it gets hot outside. Not a problem in fall, winter, or spring, but summers at 100 degrees is hard on bleach. Was it stored in a hot warehouse before I got it? Just how hot is it in that shed outside in the sun? The garage was at 100 degrees, shed could be hotter.
    I asked about this at the pool shop where I get my 12.5%. What the guy told me is, they use it in their own pool service business, and get two deliveries a week. He also said the plant is relatively nearby, it's probably only 1-2 days old when they get it.

    I have 90F+ days routinely where I live. Earlier this summer I did a fairly careful measurement of the last jug in a batch of 12.5% I'd bought about 6 weeks earlier; it was down to about 9.5%. I do keep it outside, but in the shade.

    I would expect that the rate of degradation slows down as the concentration goes down; that is, after your 12.5% degrades to 6.25% (a few months outside in the summer?), from that point on it should last as long as fresh 6.25% bleach. The only reason that would be true is if degraded 12.5% is somehow chemically different from fresh 6.25% in a way that affects the stability of the remaining hypochlorite.
    --paulr
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  11. #11
    Senior Member
    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    9,183

    Re: Does liquid chlorine go bad?

    It mostly works the way you described where the rate of loss is faster at first and as the concentration drops the rate of loss slows down. The rate of loss varies very roughly as the square of the concentration, so it's not linear.
    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"

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •