Calibrating Refractometer

[Reef Pilot]

I got some 35 ppt calibration fluid yesterday, and just checked it with my Sybon refractometer. It was bang on perfect. I had previously only checked it with the supplied 0 ppt ultrapure water fluid but have never had to adjust it. Now with the 35 ppt fluid, glad to see that it is accurate at both ends.

I've had the refractometer now for over 3 years, and use it often with water changes and with my QT tank. Not sure how they can get out of calibration, but mine has stayed true the whole time.