Calibration solution?

[Notsolostfish]

Why when i calibrate for example my BRS refractometer with the calibration fluid it comes its different results? For example. I calibrated my BRS refractomer with the calibration solution they provided. And i adjusted the screw as it was off by 2ppm. Then i bought fritz calibration solution. And the solution was off too. Why is that? Is that means the solutiob itself is not accurate?

 

[Dan_P]

Why when i calibrate for example my BRS refractometer with the calibration fluid it comes its different results? For example. I calibrated my BRS refractomer with the calibration solution they provided. And i adjusted the screw as it was off by 2ppm. Then i bought fritz calibration solution. And the solution was off too. Why is that? Is that means the solutiob itself is not accurate?

I assume you mean off by 2 PPT.

If you are calibrating the refractometer with the reference solution, what solution are you using that is telling you the refractometer is off 2 PPT?

 

[Dburr1014]

Why when i calibrate for example my BRS refractometer with the calibration fluid it comes its different results? alibrated my BRS refractomer with the calibration solution they provided. And i adjusted the screw as it was off by 2ppm. Then i bought fritz calibration solution. And the solution was off too. Why is that? Is that means the solutiob itself is not accurate?

What does the calibration solution say?
Example; I have one that says 33sg
So when I adjust the screw, it has to say 33sg when finished calibrating.

 

[exnisstech]

Could be one fluid is bad? I made a bottle using Randy's recipe shown below and it came out to a perfect 1.026 (35ppt) compared to a fluid I had and tested with 2 refractometer and a digital tester. If you search there is more info on the recipe and other more technical methods to make it. I. Just used easy peasy method because I don't have a scale to measure small amounts.

 

[EricR]

I'd say it's definitely possible for one of the calibration standards that you bought to be "off". Initial assumptions first:
-- both are Refractometer calibration standards, not meant for some other method
-- both are allegedly 35 ppt

It's cheap and easy to make Randy's DIY standards so you'd have a point of reference -- just follow the Refractometer Standard section and be prepared for some reading:

Salinity Standards

*make a lot so minor measurement inaccuracies will have less of an impact

EDIT -- disregard, previous post came in at same time with excerpt so you don't have to read through the whole page

 

[Reef.]

I would make your own, yes your bought one is most likely incorrect.

Buy some 0.01g scales and make Randy’s DIY SOLUTION.

3.65g of table salt in 96.35g rodi water, get the measurements as precise as possible, I personally wouldn’t use the coke bottle method as it’s not as precise, you might as well stick with your bought solution.