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Thread: KH Director readings always the same, no matter what?

  1. #11
    Join Date
    27.04.2017
    Location
    Nyon, Switzerland
    Posts
    75

    Default

    I recalibrated the KHD pH probe. It took me three tries to calibrate at pH 4: I got a "calibration failed" error message on the first two tries. The calibration at pH 7 worked the first time.

    I then took a measurement using the KHD and the Hanna. Hanna 7.7 KH and KHD 6.8 KH...

    So I guess it was not a calibration issue. What now?

  2. #12
    Join Date
    27.04.2017
    Location
    Nyon, Switzerland
    Posts
    75

    Default

    By the way, the rise in KH shown by the Hanna checker is to be expected: as I mentioned, I increased the daily Carbonate dosing by about 15% in order to help raise the KH from the initial measurement of 6.8.

    What is frustrating is that the KHD is not reflecting that increase in dosage...

  3. #13
    Join Date
    27.05.2015
    Posts
    2,488

    Default

    Please open a support ticket and reference this thread so we can provide further assistance.

  4. #14
    Join Date
    27.04.2017
    Location
    Nyon, Switzerland
    Posts
    75

    Default

    Ticket opened...

  5. #15
    Join Date
    31.01.2019
    Posts
    2

    Default oxygen probe

    Quote Originally Posted by Ziemowit View Post
    Hello,
    I have an identical problem.
    Ziemowit
    Hello,
    Does anyone have an oxygen probe connected?
    Ziemowit

  6. #16
    Join Date
    23.03.2018
    Posts
    19

    Default

    Quote Originally Posted by Laith_61 View Post
    Ticket opened...
    Hello, i have now same problem, do you fix it?

  7. #17
    Join Date
    27.04.2017
    Location
    Nyon, Switzerland
    Posts
    75

    Default

    Well, yes.

    I think one of the problems of moving to a KH control system to measure and control KH is that these systems use a completely different methodology to measure KH than what the average hobby test kit does: titration of a reagent with pH measurement instead of a colour titration (either visually or via a colour detection system such as a Hanna Checker). In fact, from what I have researched, this is one of the most accurate ways to measure KH.

    My conclusion is the following:

    1. It does take the KHD several if not quite a few measurements to "settle" down and start showing consistent results as well as showing correct changes in KH.

    2. You have to accept that even if the KHD readings seem to be different from your usual KH test method, once they show consistent results, you should trust them. For me, this was the most difficult "psychological" obstacle to overcome as you can see from my posts.

    3. More important than the actual KH figures is the ability of the KHD to measure and, through it's control capability, keep the KH within a set level... once again consistency.

    So I have set the KHD to control my KH with a nominal value of 8 KH and it is doing a good job of doing that (using the adaptive mode of control). My Hanna KH checker may not show 8 KH (I haven't tested that) but even if it showed 7.5 it still means that I now have a way of keeping it at a consistent level of 7.5...

    That is enough for me and my corals are not showing any adverse effects after two weeks of the KHD controlling the KH.

    Not sure if that answer is as clear as it could be but I am now happy with what the KHD can and is doing!

    Laith

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