What kind of refractometer?

[W1ngz]

Way back when I was still on my first ever bucket of salt, I learned that plastic hydrometers are basically crap. I bought a relatively cheap refractometer online somewhere, and it's been fine, but lately the calibration seems to change from one week to the next, so it's up for replacement.

Looking around, I'm seeing distinctions between 'standard' and seawater refractometers. Some put the same thing in a pretty branded box, and re-sell it for 2.5 times the price.

Mostly the difference seems to be in the scaling, where a normal one will read 0-100 ppt. a seawater will be scaled only to about 40. Narrower scale, more precision? Is that the only difference? Does it really make a difference at all?

 

[clm65]

Instrument accuracy is frequently given in percent of scale, so I would say yes, the narrower scale should give you a little more accuracy. But more importantly, the narrower scale should also be easier to read.

And they don't need to be expensive. I have a cheap one that works well (I don't recall the brand). I was browsing websites, looking at new ones recently, and some of the worst reviewed refractometers were more expensive than those with good reviews.