Conductivity Meters: pinpoint vs used lab grade units

Discussion in 'Reef Chemistry by Randy Holmes-Farley' started by Velcro, Sep 24, 2017.

  1. Velcro

    Velcro Well-Known Member

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    hi randy,
    I'm thinking about picking up a conductivity meter. Pinpoint originally came to mind, but after reading some I understand that it's temp compensation is quite slow. I see several used older Orion 105 handhelds on eBay for the same price as a new pinpoint. How resilient are the probes on these things? Should I just buy a new pinpoint and deal with the slower comp?
     
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  2. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    My Pinpoint was definitely slower than my Orion 128. Not more than a couple of minutes or so, but slower.

    The probes are pretty tough, relative to probes like pH.

    Hard to know which way to go. :)
     
  3. Velcro

    Velcro Well-Known Member

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    Thanks for the reply. I ended up going with a thermo orion 105A+ that was about $20 less than a new pinpoint. Definitely some cosmetic use, but I'm told it works well :)

    [​IMG]
     
  4. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    Do you know if it is a 4 electrode probe?
     
  5. Velcro

    Velcro Well-Known Member

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    Unsure, can you tell from the connection?

    [​IMG]
     
  6. Velcro

    Velcro Well-Known Member

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    Crap, it looks like there's a chance that the included probe is only for up to 20 mS/cm!!!
     
  7. Velcro

    Velcro Well-Known Member

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    @Randy Holmes-Farley I think i dodged a bullet. Looks like the cell that only goes to 20mS/cm has a 1m cord while mine clearly is longer which narrows it down to just one possible conductivity cell.
    upload_2017-9-25_11-14-21.png
    Here's a picture of the same meter but with the 1m cord and the 20mS/cm cell:
    [​IMG]
     
  8. Velcro

    Velcro Well-Known Member

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    I managed to get the probe info. It is a 4 electrode with a range from 1 microS/cm to 200 milliS/cm
     
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  9. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    Nice! :)
     
  10. Velcro

    Velcro Well-Known Member

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    Now if I could just find a manual!
     
  11. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    lol

    My 128 was more simple, with the only user adjustable setting was the range, plus an on/off switch. :)
     
  12. Velcro

    Velcro Well-Known Member

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    Cole palmer came through with a PDF of the manual!
     
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  13. Velcro

    Velcro Well-Known Member

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  14. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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  15. Velcro

    Velcro Well-Known Member

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  16. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    You're welcome.

    Happy Reefing. :)
     
  17. Velcro

    Velcro Well-Known Member

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    I got the meter, it works GREAT! One interesting thing that I found though.

    I got a new bottle of Pinpoint salinity calibration solution. This is supposed to be able to be used for conductivity meters as well as refractometers. Being that it says 53.0mS = 1.026 SG = 35.0ppt I can only assume that it must not be pure KCl, as my understanding is it would not be possible for KCl to show all of these things on both devices without being two different concentrations. This meter works by entering the cell constant in the settings and then measuring a known standard. If it is off, you adjust the cell constant by a percentage until your meter reads the correct conductivity for the corresponding standard. All said and done, I had to adjust the meter down about 1.04%. I didn't really believe this number to be honest, because I tested it on a fresh batch of saltwater I'm mixing and it was showing 32ppt.

    Here's where it gets interesting. I used your conductivity calibration solution DIY and made up a pure KCl standard. I used a jewelers balance which reads to 0.01gm. I weighed the appropriate amount of RODI and KCl USP. I then reset the meter to it's default cell constant and tested the DIY KCl solution. BAM 35.0 ppt EXACTLY. I didn't write down the exactly mS/cm... 35.0ppt is close enough for me.

    Also this thing is stupid fast. Temp adjusts in 5-10 seconds. I guess you get what you pay for when the probe was over $500 new!
     
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  18. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    The Pinpoint fluid is supposed to be 53 mS/cm. It is a seawater mimic, so is good for most devices.

    Glad the standard worked!
     
  19. Tim Olson

    Tim Olson Love to Learn! R2R Supporter Partner Member 2018

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    To clarify ... I currently use the Pinpoint fluid to calibrate my Pinpoint Salinity Monitor to 53 mS/cm. Is that the most accurate method or should I use your DIY solution, like Velcro did?

    Thanks :)
     
  20. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Expert Contributor Article Contributor

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    Assuming the Pinpoint solution is made as claimed (and not left open to the air to evaporate, etc.), then it is perfect for calibration. :)
     
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