Refractometer and Hydrometer have different readings

[marino420td]

Deep Six Hydrometer shows SG of 1.026
Refractometer show SG of 1.030

The refractometer was calibrated using RO/DI water with a zero reading.

Do I just assume that the refractometer is the correct one and adjust my SG using it?

[Randy Holmes-Farley]

The refractometer is more likely to be accurate than is the Deep Six, but I do not recommend just accepting refractometers as accurate either.

See this thread:

http://www.reefcentral.com/forums/showthread.php?s=&threadid=953605

[Randy Holmes-Farley]

My Deep Six read low when I tested it for this article:

Specific Gravity Measurement
http://www.advancedaquarist.com/issues/jan2002/chemistry.htm