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Thema: KH Director reading too high - tried a lot of the known fixes

  1. #1
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    17.03.2021
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    Standard KH Director reading too high - tried a lot of the known fixes

    Hi
    I've recently setup a KH Director and it is still reporting high dKH. Reports around 2-3 dKH higher than actual value. Here is what I have tried, some of it several times

    1. Measured and remeasured all the lines
    2. Calculated volume by disconnecting and dispensing into a 50ml graduated cylinder - twice - this was within 2ml of measured/ calculated volume by length
    3. Re-calibrated pH probe 3 times - all readings after calibration have been within .2 of 4 and 7
    4. Re-calibrated dosing heads twice - each calibration within 0.5ml of each other
    5. Checked for air bubbles, multiple flushing and venting reagent
    6. I ordered some GHL KH reference fluid and its ran three times 10.2, 10.1 and 10
    7. Hanna checker gives me a dKH of 8 (tank water)
    8. KHD gives me a consistent 10.3
    9. Saltwater is Tropic Marin Pro made up to std strength i.e. 1kg/30litres which should be about 7-8 dKH

    I really don't know what else to check, the only thing which is odd is the waste is being reported much higher than is being produced - waste on dosing pump 3 is showing as 1439ml in the container at most its 950ml - this has been consistently high

    Thanks

  2. #2
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    07.05.2020
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    Consistency is the key ... my KHD records between 9.5 and 10 testing twice a day. Recent Triton N-Doc test shows 9.8.

    I could never get Hanna tester to agree so stopped using it.

    If the KHD is accurate versus the ref fluid then I would be happy

  3. #3
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    17.03.2021
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    That's the problem, it isnt accurate versus a brand new GHL KH reference fluid, I've now done 4 tests with the reference fluid 10.2, 10.1, 10 and 10.5

  4. #4
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    07.05.2020
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    Zitat Zitat von Row1974 Beitrag anzeigen
    That's the problem, it isnt accurate versus a brand new GHL KH reference fluid, I've now done 4 tests with the reference fluid 10.2, 10.1, 10 and 10.5
    That's 10, 10, 10 and 10

  5. #5
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    17.03.2021
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    Zitat Zitat von Bob_The_Reefer Beitrag anzeigen
    That's 10, 10, 10 and 10
    Yes but it should be 7.5, 7.5, 7.5 and 7.5 (+/- 0.2) - its consistent but it isnt within the tolerance of the reference solution so why would it be consistently high
    Geändert von Row1974 (17.03.2021 um 13:21 Uhr)

  6. #6
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    What sample volume are you using?

  7. #7
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    Zitat Zitat von Bob_The_Reefer Beitrag anzeigen
    What sample volume are you using?
    80ml

  8. #8
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    07.05.2020
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    So you've consumed 320ml of reference solution?

  9. #9
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    Zitat Zitat von Bob_The_Reefer Beitrag anzeigen
    So you've consumed 320ml of reference solution?
    looking at the bottle yes, its almost half gone

  10. #10
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    Then I can only suggest raising a ticket to verify the probe is not faulty .... sorry

    BTW my waste output is much less than reported too ... to answer the final question in your original post

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