Refractometor???

coral88 · May 4, 2008

Iâ€™m going to order a refractometer and canâ€™t tell if there is any real difference in the $50 ones or the ones that cost $80 or more.
What do you get for the extra money other than a light or a nicer looking device?
Will a $50 work just fine?
Please suggest one if you know of a good one.

revhtree · May 4, 2008

YES get the $50 one. I have had mine for a few years and still doing great!

coral88 · May 4, 2008

So as far as accuracy goes, there is no real difference for the extra money?

J. Montgomery · May 4, 2008

Most of the big online stores sell the same generic refractometer for ~$50, the only difference being the sticker on the outside. I have one and its served me well. You can make your own salinity reference solution to calibrate it at 1.026. That DIY recipe is summarized at the bottom of this article:
http://reefkeeping.com/issues/2006-12/rhf/index.php

Russellaqua · May 4, 2008

My only suggestion would be just to make sure it has an automatic temperature compensation feature. Small changes in temperature can effect the index of refraction and change your reading.

coral88 · May 4, 2008

Any brand recommendations?

Russellaqua · May 4, 2008

I can't really recommend any specific brand. Mine is a generic cheapo. The first one I got didn't even have the plate in it so you could read the salinity! LOL! The second one did and it works great. I highly recommend any refractometer over a hydrometer. The latter is just far too inaccurate for my liking.

coral88 · May 4, 2008

I just ordered one by Milwaukee Instruments It was $77.80 with shipping but I like that it is a brand I recognize. I don’t know if it comes with calibration fluid. Should I order some or just calibrate with RO/DI?

J. Montgomery · May 5, 2008

coral88 said:
I don’t know if it comes with calibration fluid. Should I order some or just calibrate with RO/DI?

Not all refractometers are accurate at both 0.000 and 1.026. Calibrating with RO/DI water to 0.000 is good for knowing the accuracy in the low end of the scale, but it doesn't necessarily mean that you're accurate at 1.026 (which is really the value you want to be measuring). I've know people to have theirs off by as much as +/- 0.004, which can be an issue when you're trying to keep certain levels of calcium, alk, mag, etc . . . .

I highly recommend the DIY salinity solution that I posted above. It's super easy to make, essentially you measure some table salt in a measuring spoon and dilute it in a 2L bottle . . . and its surprisingly accurate. It costs virtually nothing.

coral88 · May 9, 2008

I got my refractometer today and here it is

I don’t have my calibration fluid yet so I put RO/DI in it just to see what it would read, and it read zero. So I tried it out with some water out of my tank that I’m assuming is at 1.025 and it read 1.025. So do I need to calibrate it, or should I assume it is calibrated?