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Thread: Ok. I think I have figured out how to tell if a cond probe is bad.

  1. #1
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    Ok. I think I have figured out how to tell if a cond probe is bad.

    Use a Apex display* and run cond calibration which will show a number.
    If the probe is in 1.025 SG saltwater, it will show over 400. If in 1.010, about 200. In RO, near 0.
    My Jan 2018 probe and my older Jul 14 both work.
    If yours doesn't change much. Let say it stays at 20 no matter what solution it is in. Then you have a bad one.

    Also look closely at the tip. My bad one is dirty INSIDE the tip bulb and from the side hole, I see white precipitation.

    * You should be able to use web interface and manual calibration to see the number. Use manual calibration so that it doesn't time out.













    I wonder what number a new probe would show at 1.025 SG.

  2. #2
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    A new probe that has been "reset" with a manual calibration unplugged usually reads between 500-700 from what I have seen in 53mS/cm.

    Sent from my SM-G965U using Tapatalk

  3. #3
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    Right. So, you can tell how much life is left on a cond probe.
    My dead one is about 40 in my 1.025SG water.

  4. #4
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    Quote Originally Posted by derekc View Post
    Right. So, you can tell how much life is left on a cond probe.
    My dead one is about 40 in my 1.025SG water.
    Cond is kinda an all or nothing in that regard. A failed probe will read nearly identical values dry vs saltwater and a good one will have a good variation.

    Sent from my SM-G965U using Tapatalk

  5. #5
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    So, I bought a NEW cond probe from BRS.
    The settling number was about 200 when I first dipped it into my 1.025 SG. So, I let it soaked for 3 days. Today it is at 342.
    Do I have to soak it for another week?
    Or brand new one should be at least 500 the moment it is in water?
    Defective?



    My old probe is instantly at 552.



    BTW, I have 2 PM2's and I have swapped the probes. The problem follows the probe.

  6. #6
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    Quote Originally Posted by derekc View Post
    So, I bought a NEW cond probe from BRS.
    The settling number was about 200 when I first dipped it into my 1.025 SG. So, I let it soaked for 3 days. Today it is at 342.
    Do I have to soak it for another week?
    Or brand new one should be at least 500 the moment it is in water?
    Defective?



    My old probe is instantly at 552.



    BTW, I have 2 PM2's and I have swapped the probes. The problem follows the probe.
    It might need a little longer to soak. Give it another day. I would also do a calibration with the probe unplugged to "reset" the probe.

    Sent from my SM-G965U using Tapatalk

  7. #7
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    For the record, currently the settling number is 451. That is about 4 days of soaking. I will wait it for to be stable for a day or hopefully over 500 before I will calibrate and start using it.



    Guys, I think that is what you always do when you get a new cond probe, otherwise it is just waste of time doing any calibration when the settling number is not even stabilized yet.


  8. #8
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    Haha. one week the settling number is still NOT SETTLING.
    No wonder people have so much trouble making cond probe work.

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