Refractometers and pressure

[Cory]

After reading this chemistry question of the day:

https://www.reef2reef.com/threads/reef-chemistry-question-of-the-day-13.174107/

I was wondering if a person who lives on top of a mountain would have their refractometer read more or less as opposed to living at sea level.

 

[Randy Holmes-Farley Verified Community Expert]

I do not believe that the air pressure is important. The density of water hardly changes with atmospheric pressure changes, and any change there is will also be happening to the calibration standards as well.