Caution for anyone using a refractometer

[fkshiu]

Originally Posted by EmilyB

I'm confused. I use a refractometer and calibrate it with RO. Never had a problem in over five years...????

Same story here - never had any problem with livestock.

However, using FRESHwater to calibrate an instrument that you use to measure SALTwater can lead to some error. Anyone who uses a pH controller knows that you have to calibrate it at several different pH points for a proper reading - this is called slope calibration.

Using a SW reference solution as per the article does the same multipoint calibration for your refractometer. Mine was out by about 0.025 SG - not a massive amount, and my livestock has always been fine. I may try to bump it up a little bit to see what happens. It would be interesting to see what an electronic salinity meter would say. Anybody out there have one?