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Thread: OTO test

  1. #1
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    OTO test

    My OTO test in the TF100 test kit measures TC.
    There is a 2 bottle test from Leslies that measures FC. Doesn’t this test make more sense? What am I missing?
    A TC could feasibly be a lot of CC & too little FC, right?

    Thanks
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  2. #2
    Senior Member The Mermaid Queen's Avatar
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    Re: OTO test

    This is why we recommend the FAS-DPD test, which tells you FC and CC. If you have the TF100, you already have this.

    when your chemistry is well-maintained, the OTO test is great for indicating a problem... if you normally have 'some' chlorine each evening, and suddenly you have none, you know you need to check with the FAS-DPD to get an accurate reading and nip the problem in the bud!

    18x32 grecian IG vinyl; ~23000 gallons; 250# sand filter, Hayward superpump with AO Smith motor 1HP SF1.0; booster pump for polaris. Handy Links: Jason's Calculator, TF-100 Test Kit, Pool School, CYA-Chlorine Chart
    "Shock" is a process, not a product!

  3. #3
    Senior Member polyvue's Avatar
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    Re: OTO test

    Quote Originally Posted by Johnny B
    A TC could feasibly be a lot of CC & too little FC, right?
    Yes, it could.

    Quote Originally Posted by The Mermaid Queen
    This is why we recommend the FAS-DPD test, which tells you FC and CC. If you have the TF100, you already have this.
    Follow commands from the deep! The Mermaid Queen has spoken...

    Get yourself a FAS-DPD kit so you can accurately test FC and CC. Leslie's (in my area) is often out of stock on the one kit they sell that works: Chlorine DPD FAS Complete Service Kit. They have other kits with similar titles. Avoid them. If you're not in love with Leslie's, you can purchase a TF100 kit from http://www.tftestkits.net/ or a Taylor K-2006 here. The Taylor K-2006 is also available from on-line retailers.

    EDIT Oh, just noticed from your initial post that you referenced the TF100, so assume that you have the FAS-DPD powder and R-0871 titrant that you need to perform the chlorine test. Definitely use this per the instructions in your kit. EDIT

    Edited by Greg 10/3/2009 9:44 pm PDT
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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  4. #4
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    Re: OTO test

    The "two-bottle test" is probably the DPD drop test, different from the FAS-DPD powder-and-drop test. The DPD test does measure FC rather than TC. Both the FAS-DPD and DPD can be augmented to test CC as well (using R-0003 if you have a Taylor-based kit).

    The DPD test is a color-matching test, like OTO, so that part is not really different (except it uses shades of pink instead of shades of yellow). However, at high chlorine levels, the DPD test can "bleach out" and read falsely low. The OTO test does not have that problem.

    In a pool that is behaving itself, CC will be low and so FC and TC will be essentially the same, and the OTO test will work well enough. In a pool that is having problems where shocking is the answer, the DPD test will bleach out and you'd need the FAS-DPD anyway. So, that's why we're not big fans of the DPD test.
    --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

  5. #5
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    Re: OTO test

    A TC could feasibly be a lot of CC & too little FC, right?
    I think you may be overlooking the primary reason the TF-100 kit has two seperate chlorine tests.

    1. Use the OTO (yellow) test to check the presence of chlorine. It is quick, very dependable and cheap to perform. Use it daily or thereabouts.

    2. When you have the need for precision, test for CC's, or test for very high levels of chlorine, then use the FAS/DPD test. It is accurate up to 50+ppm (in increments of .2ppm if you really want to be precise) and will report the presence of CC's very dependably.

    If you use those two tests as they are intended, the DPD test you are talking about is redundant and, if you use it in place of the OTO, costly.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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    TFTestkits , PoolMath , Pool School

  6. #6
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    Re: OTO test

    Thanks that helps.
    I just happened to have that Leslie’s DPD 2-bottle test from pre-TFP days so I used it all summer after the pool behaved, so essentially all summer.
    Recently ran out, so started suing the OTO.
    I simply found the DPD 2-bottle test easier to read/ more accurate, based on my testing with both the OTO and the FAS-DPD minutes apart (just like I did when I fist started using the DPD 2-bottle test early in the summer).
    With the OTO I was under or over chlorinating, without creating a problem, just seemed to be silly to under or over chlorinate (I’m sure the same is true when I used the 2-bottle test, just less so, because I measured it on several occasions); for the price of 1 more bottle per summer, I can more accurately chlorinate, not for accuracy sake, for bleach expense & algae issues.

    It could just be my eyes, but my guess is that others would have similar findings.

    And yes, that 2-bottle test has another bottle to measure CC, which I never did, for CC I use my test in the TF100 kit

    Thanks again for the great info.
    19,800 gallons (closed/winter 18,654 gal); plaster; 18x34 Ft kidney bean shape, Depth 3Ft-5Ft. Built 1992
    Pentair Whisper Flow Pump 1HP. Winter safety cover w anchors.
    Sand filter, Pentair Sand Dollar Top Mount Model SD80; Effective Filtration Area 3.5SF
    - FlowRate 75GPM, 8Hr 36,000, 10Hr 45,000, 12Hr 54,000; Pressure Weight 50PSI
    BBB (Hayward Chlorinator when leave town). Polaris 360 cleaner.

  7. #7
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    Re: OTO test

    Many people have trouble reading the shades of yellow on the OTO test, including me. I am trying to train myself to use it, but it's more a matter of "that dark means I can skip today" or "that light means run FAS-DPD to see how much I need" rather than learning how to distinguish 4.5 from 5.0.

    This whole process works best on a stable and well-mannered pool, of course.
    --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

  8. #8
    Junior Member ThePaul's Avatar
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    Re: OTO test

    Quote Originally Posted by PaulR
    However, at high chlorine levels, the DPD test can "bleach out" and read falsely low. The OTO test does not have that problem.
    How high is "high chlorine levels" in this context?

  9. #9
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    Re: OTO test

    Generally, chlorine levels above 10 ppm will start to bleach out the DPD test. Even above 5 ppm, the chlorine starts to interfere with the test, but this can be accounted for with the calibrated comparator tube (though most tubes only read to 5 ppm anyway).
    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"

  10. #10
    Senior Member polyvue's Avatar
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    Re: OTO test

    Quote Originally Posted by ThePaul
    Quote Originally Posted by PaulR
    However, at high chlorine levels, the DPD test can "bleach out" and read falsely low. The OTO test does not have that problem.
    How high is "high chlorine levels" in this context?
    As chem geek said, 10 ppm and over may cause the solution to become clear ("bleached out") or at least clearer. If you suspect high chlorine, you can test this notion by adding 1 drop of R-0002 DPD reagent to the sample and watch for a quick flash of pink... or starting from an empty comparator tube, add 5 drops each of R-0001 and R-0002 followed by a few drops of sample water. If the sample turns pink, chlorine is high.

    This testing problem can be redressed by preparing a diluted sample and adding together the ratio components for the multiplier. For example, a 1:1 dilution created from pool water and distilled water (or from the tap--sufficient for a rough estimate) can be tested, then multiply the test result by 2 (1 + 1)... for a 2:1 dilution with distilled water, multiply the result by 3, etc.
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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  11. #11
    Junior Member ThePaul's Avatar
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    Re: OTO test

    Thanks chem geek and poyvue.

  12. #12
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    Re: OTO test

    Are there any complications with too much chlorine? I may be having this problem with a green pool.

    The initial test results were FC:0;PH:8.0, TA:70;CH:170; CYA:60 TDS:1200ppm;Phosphates:0. Lesiie's Pool tested the TDS and Phosphate.

    It is a 20,000 pool. I added 8gallons of liquid chlorine to super chlorinate and 1g of Muriatic acid(too much), and added 8ozs of Ultra Bright step 5 Enhancer. It is also a inground pool that utilizes a 3/4hp pump and has a filter cartridge system. It is a plaster style pool.

    I ran the pump for 18hours and the next day it was a lighter shade of green. I retested to find that the chlorine was 0; and the ph dropped to 7.0. I also bought a phosphate tester to find out it was about 200ppm. I also tested for ammonia and the results were .25ppm.

    Today I went back and retested chlorine which was maybe a 0.2ppm;ph 7.0. I asked the help from another pool guy and he told me to introduce 4gallons of chlornie and 7ozs of dropout. I timed the timer to run for 4 hours and then shut off for the rest of the day. I am hoping tomorrow the algae will be dead and ready to vac out.

    Does it look like I took the right actions?
    Glad to help with any issues that I can. Send me a pm.
    http://www.starbrightpool.com

  13. #13
    Senior Member polyvue's Avatar
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    Re: OTO test

    Quote Originally Posted by starbrightpools
    I may be having this problem with a green pool.

    The initial test results were FC:0;PH:8.0, TA:70;CH:170; CYA:60 TDS:1200ppm;Phosphates:0. Lesiie's Pool tested the TDS and Phosphate.

    It is a 20,000 pool. I added 8gallons of liquid chlorine to super chlorinate and 1g of Muriatic acid(too much), and added 8ozs of Ultra Bright step 5 Enhancer. It is also a inground pool that utilizes a 3/4hp pump and has a filter cartridge system. It is a plaster style pool.

    I ran the pump for 18hours and the next day it was a lighter shade of green. I retested to find that the chlorine was 0; and the ph dropped to 7.0. I also bought a phosphate tester to find out it was about 200ppm. I also tested for ammonia and the results were .25ppm.

    Today I went back and retested chlorine which was maybe a 0.2ppm;ph 7.0. I asked the help from another pool guy and he told me to introduce 4gallons of chlornie and 7ozs of dropout. I timed the timer to run for 4 hours and then shut off for the rest of the day. I am hoping tomorrow the algae will be dead and ready to vac out.

    Does it look like I took the right actions?
    Welcome to TFP

    Adding enhancers and clarifiers to the pool without first addressing the likely issue is not getting you anywhere, so would recommend that you pause from adding anything more to the pool and read these two short articles:

    pool-school/defeating_algae

    pool-school/shocking_your_pool

    The chlorine keeps dropping because it is finding organic matter to oxidize (and some of it is being destroyed by sunlight, but disregard this for now.) To combat algae, you need to have a plan of action. Use this chart to determine what level of chlorine is needed to shock the pool. Adjust pH, if necessary (to 7.2 - 7.6), before shocking. Then add enough chlorine to come up to shock level and add more every few hours as needed to maintain that level until an overnight Free Chorine test demonstrates that there is no longer a demand on your chlorine. (This is discussed in articles above.)

    So, to answer your more specific question, if you started with FC of 0 and added 8 gallons of 6% liquid chlorine (bleach) this doesn't sound like too much. Not sure about the muratic acid... this may have been too much. Suggest that you test the water again (pH and FC) to see where you are now. Don't stop until you are able to conduct an Overnight Free Chlorine Test and it shows less than 1 ppm FC loss.

    If you have questions about this process, post back -- many thousands of people here have been in your situation before and understand what's needed, so you'll find good advice here.

    Good luck!
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    View of spiral galaxy in Ursa Major NGC6217 - Hubble Telescope 2009

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