Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 15 of 15

Thread: Testing strength of liquid chlorine

  1. Back To Top    #1
    ktdave's Avatar
    Join Date
    May 2007
    Location
    Katy, TX
    Posts
    888

    Testing strength of liquid chlorine

    The stoichiometry of this is hurting my brain. I've got some 10% (originally) liquid chlorine in the garage that I'd like to know the "current" strength of. I've seen how to test this on here somewhere before, but I can't find it.

    TIA
    11,000 gal. gunite w/midnight blue and white pearl PebbleTec
    Intelliflo 4x160 pump
    Intellichlor IC-20 SWG
    Pentair cartridge filter 420 sq. ft.
    Mastertemp 400K BTU heater
    Legend Platinum cleaner
    Pool School
    JasonLion's Pool Calculator
    TF Test Kits

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,887
    If you do a 9999 to 1 dilution with chlorine free water the resulting concentration in ppm will equal the original concentration in percent. There are various ways to do the 9999 to 1 dilution, none of them particuarly easy to get right without some lab equipment. One thing you can try is 10 ml of bleach into a 1 liter soda bottle and then dilute that again 10 ml to 1 liter. Most people have a test kit vial which can measure 10 ml and 1 liter soda bottles are not that difficult to come by.
    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
    ktdave's Avatar
    Join Date
    May 2007
    Location
    Katy, TX
    Posts
    888
    Thanks Jason!
    11,000 gal. gunite w/midnight blue and white pearl PebbleTec
    Intelliflo 4x160 pump
    Intellichlor IC-20 SWG
    Pentair cartridge filter 420 sq. ft.
    Mastertemp 400K BTU heater
    Legend Platinum cleaner
    Pool School
    JasonLion's Pool Calculator
    TF Test Kits

  4. Back To Top    #4
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    389
    I've only tried it three times before (at the same sitting with three different bleach suppliers) and found that my mixing method needs improvement. I took two samples from each bucket at a minimum of 10 minutes apart. I found that none of these second samples backed up the first measurement.

    Because I couldn't repeat the measurement results I scraped all the measurements. I'll be trying again to get something that repeatable...and I'll be paying a bit more attention to my mixing methods.

    Check out the post in this thread by CarlD.

    let us know what you come up with.
    thanks,
    dan


    oh...you can also get 1ml syringes from your pharmacy.
    21' Aqua-Leader AGP (10,200 gallons).
    Hayward cartridge filter and two speed pump.
    Aqua-Cal HeatWave 100k (HeatPump)
    Salt 3200ppm (in non-salt water pool)
    Borates 20ppm (slowly raising)
    Aqua-Rite SWG

  5. Back To Top    #5
    ktdave's Avatar
    Join Date
    May 2007
    Location
    Katy, TX
    Posts
    888
    I tried what Jason suggested (somewhat), but I halved the volumes. I used a 0.5 liter (2cup) pyrex measuring cup and one of those syringes from the Target pharmacy with 1 ml increments. I measured 0.5 liter water filtered with a PUR filter and added 5 ml 10% liquid chlorine. I mixed well, then collected a 10 ml sample for analysis with the TF100 using FAS/DPD titration. When the DPD powder was placed in the vial, no color change. Tried several times and just kept getting a clear, colorless sample.

    May have to be much more accurate at measuring than I have capability of as Jason suggested with lab equipment.
    11,000 gal. gunite w/midnight blue and white pearl PebbleTec
    Intelliflo 4x160 pump
    Intellichlor IC-20 SWG
    Pentair cartridge filter 420 sq. ft.
    Mastertemp 400K BTU heater
    Legend Platinum cleaner
    Pool School
    JasonLion's Pool Calculator
    TF Test Kits

  6. Back To Top    #6
    ktdave's Avatar
    Join Date
    May 2007
    Location
    Katy, TX
    Posts
    888
    Ahhh! Just read the Carl D post from pool forum that gonefishin supplied. I should have used ten times the water, so 5 liters! Guess I'll have to try again.
    11,000 gal. gunite w/midnight blue and white pearl PebbleTec
    Intelliflo 4x160 pump
    Intellichlor IC-20 SWG
    Pentair cartridge filter 420 sq. ft.
    Mastertemp 400K BTU heater
    Legend Platinum cleaner
    Pool School
    JasonLion's Pool Calculator
    TF Test Kits

  7. Back To Top    #7
    CRG_80cc's Avatar
    Join Date
    Jul 2007
    Location
    Nor-Cal
    Posts
    81
    ktdave

    You’ll get better accuracy if you do two 1:100 serial dilutions of your sample (still gives 1:10,000 dilution).

    If you can measure 100mls, do your dilutions this way:

    Measure 100mls of water and place in a cup.
    Using your 1ml syringe, remove 1 ml of water
    Add 1ml of your 10% Bleach solution and mix well.
    This is your first 1:100 dilution

    To another cup, add 100mls of water.
    Using your 1ml syringe, remove 1 ml of water
    Add 1ml of your 1:100 dilution solution from the above step and mix well.
    You now have your 1:10,000 dilution needed for your test
    30K gal. IG Free form
    Cartridge Filter, Solar and Gas Heater
    Using BBB

  8. Back To Top    #8
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    389
    Quote Originally Posted by CRG_80cc
    ktdave

    You’ll get better accuracy if you do two 1:100 serial dilutions of your sample (still gives 1:10,000 dilution).

    If you can measure 100mls, do your dilutions this way:

    Measure 100mls of water and place in a cup.
    Using your 1ml syringe, remove 1 ml of water
    Add 1ml of your 10% Bleach solution and mix well.
    This is your first 1:100 dilution

    To another cup, add 100mls of water.
    Using your 1ml syringe, remove 1 ml of water
    Add 1ml of your 1:100 dilution solution from the above step and mix well.
    You now have your 1:10,000 dilution needed for your test

    Thanks CRG 80cc

    I've tried this method a couple times now...and I've come up with nice repeatable results.

    thanks!
    dan
    21' Aqua-Leader AGP (10,200 gallons).
    Hayward cartridge filter and two speed pump.
    Aqua-Cal HeatWave 100k (HeatPump)
    Salt 3200ppm (in non-salt water pool)
    Borates 20ppm (slowly raising)
    Aqua-Rite SWG

  9. Back To Top    #9
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    389
    I bought another 5gallons of chlorine to test the rate of deterioration that I get during more moderate temperatures. When I picked the chlorine up they said the truck had just dropped off a new load and the percentage was near 18%. I plan to test once a week on Saturdays.



    Sept 24 - 18% (stated from the water treatment store)
    all other results were tested by myself using the two 1:100 serial dilution method described by CRG_80cc.
    Sept 29 - 15%



    dan
    21' Aqua-Leader AGP (10,200 gallons).
    Hayward cartridge filter and two speed pump.
    Aqua-Cal HeatWave 100k (HeatPump)
    Salt 3200ppm (in non-salt water pool)
    Borates 20ppm (slowly raising)
    Aqua-Rite SWG

  10. Back To Top    #10
    CRG_80cc's Avatar
    Join Date
    Jul 2007
    Location
    Nor-Cal
    Posts
    81
    Quote Originally Posted by gonefishin


    Thanks CRG 80cc

    I've tried this method a couple times now...and I've come up with nice repeatable results.

    thanks!
    dan
    Hi Dan

    Your welcome. Just wanted to pass on how we would do the dilution in the lab when testing something. Alot less hassle than trying to measure 5 liters and better reproducability as you have seen.
    30K gal. IG Free form
    Cartridge Filter, Solar and Gas Heater
    Using BBB

  11. Back To Top    #11

    Join Date
    Mar 2007
    Location
    Coastalish 'down easter'
    Posts
    4,160
    Oh man, another scientist Thankfully I just bought a bottle of aspirin and a 12 pack

    I truly appreciate the info you guys share here, but it takes a little time and repetition for it to sink in to my head
    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!)

  12. Back To Top    #12

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    Quote Originally Posted by gonefishin
    Sept 24 - 18% (stated from the water treatment store)
    Sept 29 - 15%
    This link shows the variability in half-life of chlorine as a function of concentration and temperature. I have something similar to this put into my spreadsheet. You show that the concentration is reduced by a factor of 15/18 = .83 over 5 days. This implies a half-life derived from 0.83 = e-k*5 or k = -ln(0.83)/5 = 0.037 so t1/2 = -ln(0.5/0.037) = 18.6 days, but this is an average from the 18% to 15% concentration.

    Using my spreadsheet, that would imply around 95F which does not sound like moderate temperatures to me so the rate of loss you are seeing is higher than predicted. I would bet that the initial concentration you received was not really 18%, but was already lower, possibly 16% since that would imply a temperature of 83F and would also make things very sensitive to error in measurement.

    Next time, I would measure the concentration when you first get the chlorine (perhaps twice, to ensure repeatability) and then measure again after 1 week, 2 weeks, 1 month. That should give you a better of idea of the true life of your chlorine source. If the loss is truly as fast as you are seeing, then the chlorine may be contaminated with heavy metal ions that catalyze the bleach decomposition reactions.

    I performed a similar sort of experiment with my 12.5% chlorinating liquid from my pool store a while ago and it showed a slow decline consistent with what was expected. The lower 12.5% lasts longer than the higher concentrations you are getting and initially measured very close to 12.5% (usually it's slightly higher at around 12.8%), but I find that storing it in my pool shed with temperatures of roughly 60F at night to 85F in the day results in a drop over 1 month (30 days) down to around 11.5% which implies a temperature of 75F which is about right as a weighted average. This is also consistent with the expected FC rise when I add the chlorine to the pool on a regular basis.

    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"

  13. Back To Top    #13
    Ohm_Boy's Avatar
    Join Date
    May 2007
    Location
    Orlando, FL
    Posts
    1,344
    I think I'm confused... should that state that the concentration was reduced TO 15/18? That's reduced BY 3/18s, isn't it? I'm sure I'm missing something, but I may need a pointer.
    [center:1kpalu48]Helpful Links: Pool School | CYA/Chlorine Chart | Pool Calculator[/center:1kpalu48]

  14. Back To Top    #14
    gonefishin's Avatar
    Join Date
    Apr 2007
    Location
    Joliet, Il.
    Posts
    389
    Hi chemgeek. I do suspect that the starting point wasn't 18% when I started, which is why I noted that I didn't take a measurement. My plan was to get a measurement as soon as I got the chlorine home...but with three kids under 5 and work...it just didn't work out.



    dan
    21' Aqua-Leader AGP (10,200 gallons).
    Hayward cartridge filter and two speed pump.
    Aqua-Cal HeatWave 100k (HeatPump)
    Salt 3200ppm (in non-salt water pool)
    Borates 20ppm (slowly raising)
    Aqua-Rite SWG

  15. Back To Top    #15

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,085
    Quote Originally Posted by Ohm_Boy
    I think I'm confused... should that state that the concentration was reduced TO 15/18? That's reduced BY 3/18s, isn't it? I'm sure I'm missing something, but I may need a pointer.
    You are right. My terminology wasn't very good. It was reduced to 15/18ths of its original value.
    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
  •