Refractometer accuracy?

[Ruth]

I have two of the portable hand held ones (I am selling one of them before anyone wonders why someone would have 2) Anyway one is a Sybon from J&L and the other is a RHS - 10ATC. I calibrated both of them and get the same reading from both. I would assume that the others were not calibrated recently because my understanding is these things are pretty accurate.

[Saltysteve]

Compare TDS meters LOL

[Psyire]

Chances are, they aren't all calibrated properly.

Good Read: http://www.reefkeeping.com/issues/2004-06/rhf/index.php

You can't just dial them to Zero, using RO/DI water. (myth)