Refractometer accuracy?
 

So what's up with these precision portable refractometers?

At the Calgary meet we compared 3 units that seemed to have a SG0.007 discrepency. I'm assuming that the other two units were calibrated and allow for temp correction aswell. Could be a case of my ignorance since I just purchased mine recently.

I have two of the portable hand held ones (I am selling one of them before anyone wonders why someone would have 2) Anyway one is a Sybon from J&L and the other is a RHS - 10ATC. I calibrated both of them and get the same reading from both. I would assume that the others were not calibrated recently because my understanding is these things are pretty accurate.

Compare TDS meters LOL :D

Chances are, they aren't all calibrated properly.

Good Read: http://www.reefkeeping.com/issues/2004-06/rhf/index.php

You can't just dial them to Zero, using RO/DI water. (myth)

What was the reading from my tank? I use a cheap hydrometer type and it says right between 1.025 & 1.026

ebay
 

How about the ones they sell on E-bay? Are they any good? They seem to cost around $25-30 and there are so many kinds. Some for beer, some for car repair and then the fish tank ones. What are the differences?

Thanks for the help

The differance in readings was actually 0.005 (I'm not so good with adding and subtracting:redface: .) The one I used read 1.027 on Snappy's water. When I find some calibration fluid near sea level I'll let you know what the real number is.
Thanks for the info.

The one made for beer sounds like it would be the most useful.
My guess is that they have different ranges and units. Cost is not always an indicator of accuracy IMO. All the ones that I seen look pretty much the same.