Refractometer, Salinity & Temperature

[MikeJT]

This may be a dumb question but after two years of using this refractometer which is supposed to auto adjust for temperature, I notice while calibrating it that the measurement move quite a lot (3-4 ppm) after sitting a while or if the temperature moves up or down. I would not expect the salinity to change with temperature that much. What am I missing?

 

[GoVols]

This may be a dumb question but after two years of using this refractometer which is supposed to auto adjust for temperature, I notice while calibrating it that the measurement move quite a lot (3-4 ppm) after sitting a while or if the temperature moves up or down. I would not expect the salinity to change with temperature that much. What am I missing?

A good one should adjust for temp.

 

[MikeJT]

A good one should adjust for temp.

Thanks, just to make sure I understand. If the auto adjustment is working right, the ppm reading on the refractometer shouldn't change as the temperature of the sample changes or settles in?

 

[SPR1968]

Well it depends on which one you have of course and yes they should adjust for temperature

The Red Sea refractometer needs calibrating before every use otherwise you get inaccurate readings. I asked Red Sea about this and they say it’s because it’s a very precise instrument! To be fare it only takes a few seconds and then it seems accurate. So if you have this one, it needs regular calibration

And salinity does change with temperature as I can see on my Apex system on the graphs