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Thread: Refractometer or conductivity probe?

  1. #1
    Join Date
    14.11.2017
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    Default Refractometer or conductivity probe?

    I've calibrated my conductivity probe on my new P4 in the 50ms fluid with the fluid floating in the sump (in a bag) next to the temp sensor and it's currently reading 1.0241 whereas my refractometer reads 1.026 - 1.027 (temp compensating D-D). The refractometer is calibrated using 35ppt fluid.

    Which do I trust? Can I adjust the reading of the probe to match the refractometer?

    Thanks

  2. #2
    Join Date
    09.11.2017
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    Please check the refractometer and the conductivity sensor with the 50ms fluid. Then you can see which one shows a wrong value and recalibrate.
    If you want to adjust the reading you can do that in GHL Control Center on the sensor page input field "Density-Offset".
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  3. #3
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    What will the 50ms fluid calibrate to on a refractometer?

  4. #4
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    50ms = 32.738ppt = 1.0247sg = 1.0247kg/l

    Conversion done here: https://www.hamzasreef.com/Contents/...Conversion.php
    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.
    Kein Support oder Reklamationsabwicklung über PM! Bitte senden Sie an die Moderatoren nur PMs bei allgemeinen Problemen mit der Verwendung des Forums! Danke dass Sie uns dabei helfen, den Support effektiv zu gestalten.

  5. #5
    Join Date
    07.04.2017
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    I prefer this calculator https://reefapp.net/en/maintenance/c...unitconversion - it will make sure to give you the convertion with temperature adjustment.

  6. #6
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    Quote Originally Posted by Thilo View Post
    50ms = 32.738ppt = 1.0247sg = 1.0247kg/l

    Conversion done here: https://www.hamzasreef.com/Contents/...Conversion.php
    I have been wondering a bit how the P4 calculate the salinity numbers:

    My temp @ 25.5c P4 measures: 51.9ms - 33.9PSU - 1.024KG/l
    Calculator @25.5c: 59.9ms - 33.9PSU- 1.0223 g/cm³ -1.0254 sg
    Calculator @ 25c: 59.9ms - 1.0224 g/cm³ - 1.0254 sg

    For me it seems like the P4 is calcuating @ 25c regardless of tank remperature. Would it be possible to force the calculation to be made by real temperature and get sg as well as KG/L?

  7. #7
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    Quote Originally Posted by Thilo View Post
    50ms = 32.738ppt = 1.0247sg = 1.0247kg/l

    Conversion done here: https://www.hamzasreef.com/Contents/...Conversion.php
    Well the 50ms GHL fluid is 25ppt on my refractometer, what is the calibration fluid made of? Does it have a proper refractive index like seawater?

    Surely the D-D refractometer isn't that far out?

  8. #8
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    Quote Originally Posted by CraigH View Post
    Well the 50ms GHL fluid is 25ppt on my refractometer, what is the calibration fluid made of? Does it have a proper refractive index like seawater?

    Surely the D-D refractometer isn't that far out?
    Did you try to calibrate your refractometer with osmos water? It should be at 0 with it

  9. #9
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    Quote Originally Posted by alekslyse View Post
    Did you try to calibrate your refractometer with osmos water? It should be at 0 with it
    Yes, 0 TDS RODI water tests as 0 on the refractometer

  10. #10
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    Quote Originally Posted by CraigH View Post
    Yes, 0 TDS RODI water tests as 0 on the refractometer
    What is the ms recorded (not kg/l)? What is your tank temperature at the same time as your report your ms?

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