Refractometer/Hydrometer/GHL

[rayjay]

First of all, if the Sybon refractometer is a standard salinity refractometer then calibrating it with water will result in error at standard salt water aquaria salinity.
Even if you have one of the few sea water refractometers, it's still recommended to use calibration fluid to set it.
http://reefkeeping.com/issues/2006-12/rhf/index.php

[gregzz4]

Firstly, I wouldn't worry about the hydrometer reading as they cannot always be trusted ( put it in a drawer and forget about it )
As for calibrating the refractometer;
Mine requires me to have the solution @ 68f. I take a digital thermometer with me and wander around my basement until I find that room temperature. Then I put a drop on the lens and wait a couple minutes for it to equalize before I close the cover. I've never had an issue with it when I do this.