Calibrating Refractometer

Discussion in 'Water Chemistry' started by Redd, Feb 8, 2016.

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  1. Redd

    Redd Astrea Snail

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    What is the proper environment to calibrate a refractometer? I have calibrated mine using fresh RODI in the same temperature room as the RODI water used. I go and test the tank water, after letting it acclimate to the meter's temp, and get .002 of a difference on the high side as the swing arm hydrometer. It's an ATC meter, and a nice one at that. Not sure which to believe or if I'm actually going through the calibration steps correctly. Thanks for looking
     
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  3. Vinnyboombatz

    Vinnyboombatz Giant Squid

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    You will need a calibration liquid to do it correctly.Also keep in mind the light source should always be the same .If you calibrate it in sunlight it will show a slightly different number when then used under a lightbulb or fluorescent fixture.Always calibrate and use the refractometer using the same light source.
     
    Last edited: Feb 8, 2016
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  4. Vinnyboombatz

    Vinnyboombatz Giant Squid

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  5. Redd

    Redd Astrea Snail

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    Ok Thanks. What about the temperature of the calibration fluid? Does it need to be at a specific temp in order to accurately calibrate?
     
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  6. Vinnyboombatz

    Vinnyboombatz Giant Squid

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    Technically but like I said most refractometers will compensate for temperature to some degree.
    Love your Dachshund.They are my all time favorites.Did you catch the weiner dog commercial during the superbowl?Awesome!!lol
     
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  7. Vinnyboombatz

    Vinnyboombatz Giant Squid

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  9. Redd

    Redd Astrea Snail

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    Yup, sure did! Thanks for the link
     
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  10. DSC reef

    DSC reef Giant Squid

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    Agree with vinny, get some calibration fluid. ATC will pretty much adjust it's self with temp. I have the red sea refractometer and when I calibrate it with the fluid I wait 45 seconds before I make any adjustments. When I'm checking my water after calibration I wait about 20 seconds. Using the same light source will ensure accuracy, I use the led daylight bulb in the kitchen.
     
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  11. Todd_Sails

    Todd_Sails Giant Squid

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    And I've GOT to add-

    Unfortunately- you often have to check the calibration fluids accduracy as well.

    We had a workshop last year in our club, everyone brought their hydrometers, refractometers,
    I brought my calibration fluid. ( I did this when others had inaccurate cal. fluids. previously)

    I mean why even buy a cal. fluid- like $9 for some salt water when you can't even trust it!!?

    My cal. fluid was consistently high on 3 of those higher tech 'Milwaukee' instruments!!
    It was about 37- when it was sold as 35.

    I'm not sure what the age of it should have an effect, mine was a few years old, always kept tightly capped.
    But from some H2O molecules leaking out of a small bottle as gasses- that would raise it some.

    NOw when I use that same cal fluid, I calibrate it to 37. I need to check it again and see if it went up more.

    Moral of the story- although we buy a cal. fluid and want to trust it......
     
  12. dacianb

    dacianb Spanish Shawl Nudibranch

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    After I almost ruined my tank with salinity above scale I calibrate with RO water+30ppt+35ppt and then I measure the water. :rolleyes:
    And the plan is to change those fluids rather often (half year interval) or until I see some discrepancies between the 3.