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Thread: FC drop test vs Daily test

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    FC drop test vs Daily test

    We have been using the colored test strips up til now and have to add chlorine every day. I just got the TF100 Test Kit. Went thru all the tests. Everything looks in pretty good shape.

    The FC drop test = 7
    But the "daily" test showed 0 chlorine.

    Why the difference? Did we do something wrong? Any guidance would be very much appreciated. TIA!
    Caldera Elation (2004) AG 500 gal spa, cartridge filter

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    JasonLion's Avatar
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    Re: FC drop test vs Daily test

    The simpler OTO test (drops turn the sample various shades of yellow, which are compared to a color chart) is not very precise about reading a specific level, but is normally very good at indicating no chlorine vs some chlorine.

    I can think of a couple of different things that might have gone wrong, but no individual one seems especially likely from your explanation. The simplest thing to check is to see if you get a similar contradiction tomorrow.

    Two of the more likely of the unlikely possibilities include: the OTO reagent might be bad, or you might have used the wrong reagent somewhere on one test or the other.
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    UnderWaterVanya's Avatar
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    Re: FC drop test vs Daily test

    Are you certain you did not accidentally use the r003 that you use to test for cc's? That happened to me last week when I had 18+ FC and the OTO registered but it was the palest yellow I have seen. I retested it realizing that I had grabbed the wrong yellow topped bottle! That time the OTO came out Orange.
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    ship of fools's Avatar
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    Re: FC drop test vs Daily test

    I had the same issues when i first bought my kit.

    I tested with the simple test and it showed 0 ...... i was just about to run for bleach in a panic when i decided to do the better test .... it showed 4 ppm or so.

    I don't even bother with the simple test any more.
    21,000 gallon inground
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    GreatCanadian's Avatar
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    Re: FC drop test vs Daily test

    It shouldn't be that way. The OTO test allows you to save the drop test reagents. I use OTO daily and the drop test weekly, or after a heavy bather load or heavy rainfall - anything out of the normal parameters. As for bad reagent, I have an old Canadian Tire test kit for CL and pH. It matches my tests for the Taylor OTO. The reagents are over 2 years old and are still fine.
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    ship of fools's Avatar
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    Re: FC drop test vs Daily test

    I went all summer on one bottle of reagent .... and still have the extra since i bought the XL kit.

    The simple test just did not work for me ..... and i prefer the improved accuracy anyway. Someone else suggested bad reagent but i just don't mind doing the drop test a couple of times a week ....... for the most part i don't even need to test since i can basically predict my chlorine level fairly accurately.
    21,000 gallon inground
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    Re: FC drop test vs Daily test

    Thanks everyone. I'll retest this afternoon and see what happens. Since I'm paranoid I did add about a cup and a half of bleach. But didn't retest after that.

    My ph was high yesterday, too. 8.2. I added some spa down since that's what I had. Wonder if that could have thrown off the FC.

    We have VERY hard water here, but the hard water test came out 0. We used 90 drops and water still didn't turn color..

    I think I need to double-check everything. I'm brand new at this so thanks for the patience!
    Caldera Elation (2004) AG 500 gal spa, cartridge filter

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