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Thread: Big bubble forming in doser to reagent tube??

  1. #11
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    22.07.2017
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    Very frustrating indeed! I have to either prime the tube every day prior to a measurement or do 3 or 4 sequential measurements in order to get the air bubble out and MAYBE get a correct reading on the 4th measurement. Besides the tremendous waste of reagent, this is not very practical and especially not reliable at all.

  2. #12
    Join Date
    07.12.2017
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    Has anyone found a work around because mine is doing the same

  3. #13
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    04.11.2015
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    Hello,

    in order to avoid t he bubbles, ensure the vent tube is above the waste water surface
    Follow this thread:
    http://forum.aquariumcomputer.com/sh...water-surface!
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  4. #14
    Join Date
    06.07.2013
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    The bubbles are forming on the output of the doser that feeds the reagent tp the KHD so I can't see how the vent tube has anything to do with it.

  5. #15
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    22.07.2017
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    Hi,

    The vent tube is way above the waste water surface, so that's not it.

    Suspecting that air is getting in through the hose connectors, I tried zip ties on the tube but that did not help.

    This picture shows the air bubble formed since the last measurement taken 15 hours ago.

    bubble2.jpg

  6. #16
    Join Date
    18.02.2009
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    Kaiserslautern
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    Quote Originally Posted by paulfars View Post
    The bubbles are forming on the output of the doser that feeds the reagent tp the KHD so I can't see how the vent tube has anything to do with it.
    yes, you are right, this has nothing to do with it, this is related to another problem
    if the waste tube is below the water surface the KHD will suck waste water into the measurement cell
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  7. #17
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    06.07.2013
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    So do you have any more ideas how we can stop the bubbles forming in the reagent tube?

  8. #18
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    I tried zip ties on the tube but that did not help.
    No, this will not help and is not necessary. The problem is not that there are leaks in the connection and air comes in that way, the problem is the dissolved air in the reagent which can form after some time bubbles.

    But we found out that the impact of some air is not as large as you may think. Keep in mind that a measurement process needs about 2-3ml, and then compare how much volume this bubble has, this is a fraction.
    According to the feedback we got so far it seems not a general problem, it seems the results are still very good.

    Anyway, to get the best results: the less air in the reagent the better.

    How?
    a) get rid of the micro bubbles - see above, worked here
    b) increase the measurements per day, so the "bubbles" have not much time to grow
    No support or warranty issues over PM! Please send PMs to the moderators only if you have general problems with using the forum! Thanks for helping us to keep the support efficient.
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  9. #19
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    18.02.2009
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    Quote Originally Posted by Fishbones View Post
    Very frustrating indeed! I have to either prime the tube every day prior to a measurement or do 3 or 4 sequential measurements in order to get the air bubble out and MAYBE get a correct reading on the 4th measurement. Besides the tremendous waste of reagent, this is not very practical and especially not reliable at all.
    we need to become a bit more concrete here now

    about what differences from measurement to measurement are we talking here?

    how many measurements do you take per day?
    No support or warranty issues over PM! Please send PMs to the moderators only if you have general problems with using the forum! Thanks for helping us to keep the support efficient.
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  10. #20
    Join Date
    22.07.2017
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    14

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    Quote Originally Posted by Matthias View Post
    we need to become a bit more concrete here now

    about what differences from measurement to measurement are we talking here?

    how many measurements do you take per day?
    I take 1 measurement per day. I prime the tube every time there are bubbles in it so I can't tell you the differences from measurement to measurement, day to day, but the only time I let the bubble go it gave a result of 12.4dKH from my usual 7-8dKH. I'll stop priming the tubes now and see how it goes.
    Taking more measurements a day could help I guess but at the moment I don't need to as I have few SPS and I would only be wasting reagent. (Shipping of the reagent to my location is expensive ie, €28,91)
    Thanks for the suggestions. Hopefully the air bubbles will all make their way out one day so I can get consistent values.

    Cheers.

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