Differences between a hydrometer and a refractometer?

[billyv]

What are the differences between a hydrometer and a refractometer? Don't they both measure specific gravity? What do each of them do? And what is the difference between salinity and specific gravity? Thanks!

 

[adrian]

They both do pretty much the same thing, although they may use different units. The refractometer is a little more expensive, but precise and will last forever if you take care of it, where as the average swing arm or float hydrometer is not accurate and needs replaced every year or so to make sure its at least close as far as accuracy goes. If you have the $, I would suggest a refractometer. HTH

 

[billyv]

Thanks for the above info. Now for part two of the question,; what is the difference between specific gravity and salinity? I think I know the answer, but would like a confirmation!