Refractometer A doesnt agree with identical Refractometer B and neither read Calibration fluid as 35PPT.

[newfly]

I use this hydrometer to calibrate/check the cheap refractometer. The hydrometer never need calibration and will need fail (until I drop it on the floor and break it. One my second one)

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[rdriggett]

Piggybacking on this question: for Amazon refractometers, do I want it to read to the bottom of the 35ppt line or the top of the line?

 

[Qwiv]

Pick one and stick to it. Depends on its calibration.

 

[JimWelsh]

While it's actually difficult to tell from this paper, I think they are attempting to align the bottom of the meniscus with the middle of the line: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871082/

 

[grizfyrfyter]

I get a floating hydrometer, the glass ones. I use that to calibrate my refractometer.

 

[thephoreefer]

Bring your water to my shop I can test it using mine, but first test it using your refractor matching the calibration fluid then Test your water

 

[phatduckk]

Measuring salinity accurately and knowing what to trust used to be stressful for me. Then I got the Milwaukee digital seawater refractometer, and it isn’t anymore.

I love mine too. Can’t go back to the manual ones

 

[newfly]

Measuring salinity accurately and knowing what to trust used to be stressful for me. Then I got the Milwaukee digital seawater refractometer, and it isn’t anymore.

How often do you have to calibrate the Milwaukee? Just calibrate my cheap refractometer after 6-month and its off by 0.002 (1.023 vs 1.025 on the hydrometer). I probably should calibrate more frequently.

 

[rdriggett]

@Danhsj checked my cal and it was good. Water was 1.024 unfortunately.

 

[H2OPlayar]

@Danhsj checked my cal and it was good. Water was 1.024 unfortunately.

1.023 to 1.026 works fine for me, so long as I am not changing it regularly. 1.024 is well within the range of where you want to be plus the accuracy of the device. I do shoot for 1.025, but also don't check more than once a month or on water change days. I do a 1.00 cal almost every time with my rodi to make sure my numbers are good (and to dissolve any salts from the sensor prior to measurement)

 

[JVU]

How often do you have to calibrate the Milwaukee? Just calibrate my cheap refractometer after 6-month and its off by 0.002 (1.023 vs 1.025 on the hydrometer). I probably should calibrate more frequently.

I’m not sure about the “have to” frequency, but it only takes 5 seconds with RODI or distilled fresh water (which I always have on hand), so I do it before use if I haven’t used it in a day or more. I’ve tested without recalibrating for a couple weeks and it was still accurate, so you certainly don’t have to redo every session, I just do it out of habit.