refractometers

I have a Milwaukee mr100atc. It was around $60 or$70. The only problem is that the pin that holds the cover plate that flips down over the prism is metal. I have to put lube on it once in a while so it will hinge correctly. I however dont think i would buy one with a plastic pin because ive heard alot of people say that the pin breaks easily. 
 It can also be hard to see the scale if you dont have good light. I usually hold it under my lights for the aquarium so i can see it. I think alot of them you will have this problem with but its worth it over a swing arm hydrometer. I know their are some out their with a light built into them.
The last thing to look for is one with auto temp compensation. With these you can test water from 50 to 86 degrees and have it be accurate.

 

I've used both the generic ones (like what you can buy on Bulk Reef Supply http://www.bulkreefsupply.com/store/refractometer-for-reading-salinity-w-free-calibration-fluid.html ) and a nicer one that I own now (a Vee Gee STX-3 http://www.globalscientificsupply.com/c/272/VEE_GEE_Scientific_43036_STX_3_Handheld_Refractometer.html ). Honestly, they all work and function the same. The cheaper ones may get rust pins and rusty on the instrument itself a little, but it's still going to work and not impact the readings. I like the Vee Gee because it's a much more solid build and made from better quality materials, but both do the same thing. Had I not got it when I bought my tank, I would not have spent the extra money on the better instrument.

--AJ

 

I vote for temp compensation, a light, and dial (rather than screw calibration). Yes, that takes the price up, but you use it often and its nice to have one that is easy to use. Spend the extra $50 to get all the bells and whistles and you'll be happier.

 

I agree completely with AJ.
I have a similar Refractometer to what Bulk Reef is selling (most likely exactly the same) only I bought it from Foster/Smith years ago and paid more money/DesktopModules/ActiveForums/themes/_default/emoticons/whistling.gif.

I've been using it since 2003 with no issues although I probably need to check the calibration...
No rust on the hinge, I believe the device is aluminum, but the paint is starting to peel a bit on the edges which I assume is from the salt water.
-Eric

 

Testing 0TDS RO water should give you a reading of 1.000. If that is correct and you are getting that reading, you probably have no reason to calibrate.