Calibrating refractometer??

Discussion in 'Salt' started by dowtish, Jun 27, 2011.

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  1. dowtish

    dowtish Horrid Stonefish

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    I have been reading numerous threads debating whether to use RO/DI or a calibration fluid. I bought mine from BRS and the insructions that came with the refractometer said to calibrate to zero with RO/DI. But BRS had put a sticker on the case saying no to do that, and included a fluid. There argument is to calibrate it to a range to where you will actually be using it. and ZERO ain't it!


    Refractometer Calibration: the Myth and Risks of using RO/DI Water - Captive
    Aquatics: An Aquarium and Ecology Blog

    Watch the video at about 1:20 YouTube - ‪Saltwater refractometer demo - BRS TV‬‏

    Anybody want to add, suggest, debate on this?
     
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  3. m2434

    m2434 Giant Squid

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  4. redmarble

    redmarble Plankton

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    I had a similar question on RC, but with my new DD ATC seawater refractometer. Several recommended using American Marine Pinpoint Salinity Calibration Fluid, which is a 53.0 mS standardized fluid. So, I went ahead and calibrated my refractometer to 35ppt with this solution, at room temperature (even though the instructions to my refractometer said to calibrate at 20C with RO water).
     
  5. djbonney138

    djbonney138 Peppermint Shrimp

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    I just ordered some calibration fluid from BRS (on a sweet group buy). I have been using the same refractometer for years by using the RO method and am very curious to see what it says. UPS claims it should be here today so I will post my results.
     
  6. juniorx

    juniorx Astrea Snail

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    I calibrate mine to 0 sg first with distilled water, then use calibration fluid, then check with distilled again.

    I never have had to adjust mine a second time when checking the calibration fluid, but I like using two different fluids to check for variance, just in case the calibration fluid ever decides to change.
     
  7. mikejrice

    mikejrice 3reef Affiliate

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    Some refractometers have some variance in readings as the range changes, so it's good to check your out with calibration fluid. If you check with calibration fluid and RO still comes in at zero, you should be fine to calibrate with RO after that. Like was said before, it's always good to have ways of double checking everything.
     
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  9. benbabcock

    benbabcock Bubble Tip Anemone

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    like junior, i calibrate with both as thats what the instructions said. fist ro/di then 35ppt fluid. i have never had to adjust it yet i still calibrate before using. just like my ph probes, the first time i decide no to calibrate its going to be wrong...
     
  10. dowtish

    dowtish Horrid Stonefish

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    I think what sparked all this was the fact that I was using it, then lost the bottle! I was doing a group buy and told my buddy to put it on his order, and he told me not to waste my money, and just calibrate to zero with rodi. So, after all this research and posting this in a few places the results definitely lean towards using it. Because depending of what refractometer you have there could be a significant difference in the calibration methods. especially for what what range we all use it in.

    so if you don't have the fluid, you better go get get you some! :)
     
  11. djbonney138

    djbonney138 Peppermint Shrimp

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    I waited all day for UPS only to find out he must have stopped by when I was in the shower, maybe I will have the delivery tomorrow:cry:
     
  12. inwall75

    inwall75 Giant Squid

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    I've had "calibration weekend" at the store numerous times so I've calibrated more of them than most people. Some refracts are definitely better than others and I would recommend using calibration fluid to be on the safe side.

    BTW, the ubiquitous refractometer model RHS-10ATC is clearly made by at least 25 different Chinese companies. Some have a thumbscrew, other's have a screw. Some have a cap for the screw, other's don't. Some have a scale that shows SG in tenths, other's don't. Some are blue, some are black, some are gray. Some of the prism covers are held on with a quality plastic and stainless steel screws, others use flimsy plastic and steel screws that will rust on you within a month or two. There's even a wide variance in the quality of the cases. Caveat Emptor!!!