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Thread: discrepant chlorine tests

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    discrepant chlorine tests

    Good morning. My pool is now open for the season 10 days. The water looks perfectly clear (but is still 65 degrees). Free chlorine test yielded 6 ppm with 0 cc's, but when I use the OTO test it registers no chlorine level. The ph is 7.6 , cya level mid thirties. Pool is 18,000gallon plaster. I'm using combination TCA and bleach for chlorination. Any ideas ?
    Thanks,
    Ann

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    JasonLion's Avatar
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    Re: discrepant chlorine tests

    TCA?

    The OTO test is a much more reliable indicator of chlorine/no chlorine than any of the other tests, all of which can be affected by other chemicals on occasion.

    Which test did you use to measure FC 6 CC 0?
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: discrepant chlorine tests

    I'm using the dpd powder and 871 to test chlorine from the tf-100 test kit

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    Re: discrepant chlorine tests

    Which reagent did you use for the OTO test R-0600 or R-0003?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: discrepant chlorine tests

    It's the taylor k-1000 that came with my tf-100. I don't have the bottle with me now so I'm not sure-but looks like the 0600 in the picture online

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    Re: discrepant chlorine tests

    The R-0003 reagent looks identical and is the incorrect reagent.

    If you correctly used the R-0600, is it colorless? If not, it has been out in the sun and is not good any longer.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: discrepant chlorine tests

    It is colorless. It lives indoors inside the box, so I don't think it's been exposed to sun.

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    Re: discrepant chlorine tests

    VERY unusual for the OTO test not to perform. Keep us posted.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Killer95Stang's Avatar
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    Re: discrepant chlorine tests

    I had this same problem last week. Since it was the middle of the week and not my complete testing day (Monday), I didn't use the DPD to backup my OTO test results. This caused me to basically shock the pool to 12ppm, before I verified that I had too high of chlorine.

    In the end, I never really figured out what the issues were, although I did clean the OTO test comparator with dish soap right before I got better readings with it.

    The moral of the story... trust your gut.. if the chlorine test seems too high or low, use the DPD to confirm.

    http://www.troublefreepool.com/confu...pd-t58947.html
    Pool done!! (backyard = work in progress) 32' x 19' inground freeform with 7' spa, baja step w/ (2) bubblers, stonescapes mini pebble finish, rock waterfall feature, 12" raised bond beam, Intelliflo VS, Whisperflo feature pump, (3) 5G Color LED's, FNS + DE 60, 400K Master Temp, Easytouch 8 w/ remote, Intellichlor IC40, Vision Classic Ceramic Kamado smoker, Margaritaville DM1000!!! Party Coming Soon!!
    TF-100 Test Kit w/ Speedstir

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    Re: discrepant chlorine tests

    Thanks everyone for your input. I just confirmed I was using the 0600 and it is absolutely colorless. It was registering chlorine levels when I used it a few days ago, but not as dark yellow as I should have seen with the level of free chlorine I was measuring using the dpd/0871 test which at the time was 6.5. Any ideas?

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    Killer95Stang's Avatar
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    Re: discrepant chlorine tests

    Only other thing I can think of is to shake the R0600 before using it. I never did that before I had any issues.
    Pool done!! (backyard = work in progress) 32' x 19' inground freeform with 7' spa, baja step w/ (2) bubblers, stonescapes mini pebble finish, rock waterfall feature, 12" raised bond beam, Intelliflo VS, Whisperflo feature pump, (3) 5G Color LED's, FNS + DE 60, 400K Master Temp, Easytouch 8 w/ remote, Intellichlor IC40, Vision Classic Ceramic Kamado smoker, Margaritaville DM1000!!! Party Coming Soon!!
    TF-100 Test Kit w/ Speedstir

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    Re: discrepant chlorine tests

    but when I use the OTO test it registers no chlorine level.
    It was registering chlorine levels when I used it a few days ago, but not as dark yellow as I should have seen...
    Was it registering SOME chlorine or NO chlorine?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: discrepant chlorine tests

    There was the palest shade of yellow, so I would call it a .5, if that's considered any chlorine

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    Re: discrepant chlorine tests

    PM sent
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Killer95Stang's Avatar
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    Re: discrepant chlorine tests

    Quote Originally Posted by houdini1
    There was the palest shade of yellow, so I would call it a .5, if that's considered any chlorine
    When I was getting false readings... that is exactly what I had... I estimated it at 0.5ppm. Since we had a little rain and it had been hot, I figured the Chlorine was that low, so I added some Chlorine. Next day I ran the test again with the same result... So I added some more Chlorine. Right as I put the last drop in the pool, I thought I should do a DPD test. Wow.. the results were at 12ppm..
    Pool done!! (backyard = work in progress) 32' x 19' inground freeform with 7' spa, baja step w/ (2) bubblers, stonescapes mini pebble finish, rock waterfall feature, 12" raised bond beam, Intelliflo VS, Whisperflo feature pump, (3) 5G Color LED's, FNS + DE 60, 400K Master Temp, Easytouch 8 w/ remote, Intellichlor IC40, Vision Classic Ceramic Kamado smoker, Margaritaville DM1000!!! Party Coming Soon!!
    TF-100 Test Kit w/ Speedstir

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    Re: discrepant chlorine tests

    As a rule, it is a good working plan to test with the OTO test for the presence of chlorine....I would not use it for dosage.

    If the OTO results are strange, do the FAS/DPD test to confirm your exact FC level and then dose.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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