old refractommeter

[nanonøkk]

ok so i bought a refractometer because i wanna get pinpoint accuracy of my tanks salinity and i have a few questions.
ok so first of it’s a fairly old refractometer it looks to be sitting on that shelf for a while will that affect how it works i opened it up and it looks brand new though.
also how do i calibrate it do i need special fluid and dose temperature mess with the reading of the salinity.
also it’s a sybon opticon series fg100sa

 

[MichaelReefer]

ok so i bought a refractometer because i wanna get pinpoint accuracy of my tanks salinity and i have a few questions.
ok so first of it’s a fairly old refractometer it looks to be sitting on that shelf for a while will that affect how it works i opened it up and it looks brand new though.
also how do i calibrate it do i need special fluid and dose temperature mess with the reading of the salinity.
also it’s a sybon opticon series fg100sa

The only way you will know is by testing.

Personally, I calibrate mine with fresh RODI water, but you can also buy solution. You just want to calibrate it at 0 with something that is 100% guaranteed to have 0% salinity. There should be a small nut that you can turn to calibrate it to the 0 line.

 

[nanonøkk]

The only way you will know is by testing.

Personally, I calibrate mine with fresh RODI water, but you can also buy solution. You just want to calibrate it at 0 with something that is 100% guaranteed to have 0% salinity. There should be a small nut that you can turn to calibrate it to the 0 line.

ok thanks for the help

 

[92Miata]

Buy calibration solution.

A refractometer showing 0 with RODI tells you nothing about what its going to read with 35ppt saltwater. You don't care about the rest of the range. 35ppt is all that matters.

So calibrate at 35ppt.


(Many refractometers are skewed - they can really only be accurate at one point. You want that point to be where you're measuring)

 

[Garf]

ok so i bought a refractometer because i wanna get pinpoint accuracy of my tanks salinity and i have a few questions.
ok so first of it’s a fairly old refractometer it looks to be sitting on that shelf for a while will that affect how it works i opened it up and it looks brand new though.
also how do i calibrate it do i need special fluid and dose temperature mess with the reading of the salinity.
also it’s a sybon opticon series fg100sa

Calibrating in RODI can be a bit off. Randy Holmes Farley has got a DIY for making your own reference solution with Table salt at 35ppt. If you ain’t got accurate scales to measure it out, just make a litre of it and chuck what you can’t keep. I’ve got a vape juice bottle full of it.

 

[nanonøkk]

Buy calibration solution.

A refractometer showing 0 with RODI tells you nothing about what its going to read with 35ppt saltwater. You don't care about the rest of the range. 35ppt is all that matters.

So calibrate at 35ppt.


(Many refractometers are skewed - they can really only be accurate at one point. You want that point to be where you're measuring)

ok it has calabration solution with it

 

[nanonøkk]

Calibrating in RODI can be a bit off. Randy Holmes Farley has got a DIY for making your own reference solution with Table salt at 35ppt. If you ain’t got accurate scales to measure it out, just make a litre of it and chuck what you can’t keep. I’ve got a vape juice bottle full of it.

oh ok thanks for the help

 

[mindme]

I just buy calibration fluid from brightwell that's set to 35ppm. I want to know for sure that my solution is accurate.

 

[Randy Holmes-Farley Verified Community Expert]

ok it has calabration solution with it

Yes, it comes with 0 ppt standard. It is not clear that such a fluid is best for our purposes. A 35 ppt standard will always be suitable (if properly made), but the standard that comes with it may not be.

The problem is that if it is a true seawater refractometer, both 0 ppt and 35 ppt will work fine for calibration (assuming it is perfectly made). 35 ppt will be suitable even if it is not perfectly made, since you are matching that salinity.

If it is a brine refractometer, then 35 ppt will give a proper calibration for seawater and 0 ppt will not. It willb e inherently inaccurate using a 0 ppt standard to calibrate, then used to measure seawater.

It claims to be good for many purposes, including but not limited to seawater, which leads me to think it is not a seawater refractometer.

But in looking closely at the scale in the brochure, it looks like a seawater refractometer since 35 ppt matches up to about sg = 1.0264. if it were a brine refractometer, the 35 ppt would match up to a sg of 1.025.

So I cannot really tell what type it is. Use 35 ppt to be sure you are good to go.

 

[nanonøkk]

Yes, it comes with 0 ppt standard. It is not clear that such a fluid is best for our purposes. A 35 ppt standard will always be suitable (if properly made), but the standard that comes with it may not be.

The problem is that if it is a true seawater refractometer, both 0 ppt and 35 ppt will work fine for calibration (assuming it is perfectly made). 35 ppt will be suitable even if it is not perfectly made, since you are matching that salinity.

If it is a brine refractometer, then 35 ppt will give a proper calibration for seawater and 0 ppt will not. It willb e inherently inaccurate using a 0 ppt standard to calibrate, then used to measure seawater.

It claims to be good for many purposes, including but not limited to seawater, which leads me to think it is not a seawater refractometer.

But in looking closely at the scale in the brochure, it looks like a seawater refractometer since 35 ppt matches up to about sg = 1.0264. if it were a brine refractometer, the 35 ppt would match up to a sg of 1.025.

So I cannot really tell what type it is. Use 35 ppt to be sure you are good to go.

ok thanks for the help