Salinity Meter vs. Refractometer

[Megalodon]

When my Sybon refractometer reads 35 pts, my Pinpoint salinity monitor reads 49 mS, or 32 pts. Both are brand-new and calibrated as per the instructions.

Which one should I trust?

[midgetwaiter]

Did you calibrate the Sybon with RO? I think that's what it comes with, if so that can cause issues.

Try calibrating the refractometer with the Pinpoint 53ms fluid. It is designed to have the same refractive index as SW and should be 35ppt Check this out for more info:

http://www.reefkeeping.com/issues/2006-12/rhf/index.php

[Megalodon]

I used the "ultra-pure" water that came with the refractometer to calibrate it.

I just tested the 53 mS fluid on the refractometer and it tested 38 pts!

Oh man... I had a marine tank for a year in the past and always went by the refractometer thinking it was absolute. Having it off by 3 pts is a big deal. It troubles me that these companies and fish stores don't tell you this.