What refractometer?

[kdogg85]

My glass hydrometer broke and I would like to get a refractometer. I hear a bunch of you guys like the ebay one's and I'll go that way. I don't have a clue what to look for as far as features and what not. Is there a certain seller I should buy from or a certain set of features to look for? Thanks in advance for any help.

[ccCapt]

Something like this 1 will work fine.

NEW! Salinity Refractometer 4 Aquarium Pond Hydrometer - eBay (item 370460931948 end time Dec-07-10 20:32:19 PST)

[kdogg85]

Thanks for the link, got one on order now.

[cmor1701d]

You wont regret it. Next time you order supplies add some calibration fluid too. It should be at 35 ppt. You can also make your own calibration solution following the Homemade Calibration Standards recipe.

[Ziggy953]

Excellent choice! Very similar to the one I used for a few years.

[speckrb]

Great link/price, I have been looking also. But maybe I am being obtuse the scale on the left is the specific gravity scale, how come the lines don't add up to 1.070? the scale should go up to 1.090 to match the number of lines in increments of .001. Maybe it explains it in the destructions? I'm sure this is the one that is in all the magazines for $50.00 so it has to be right.

[redneckgearhead]

Originally Posted by speckrb

Great link/price, I have been looking also. But maybe I am being obtuse the scale on the left is the specific gravity scale, how come the lines don't add up to 1.070? the scale should go up to 1.090 to match the number of lines in increments of .001. Maybe it explains it in the destructions? I'm sure this is the one that is in all the magazines for $50.00 so it has to be right.

What an eye! I never noticed. I have ordered this same one should be here in a week or so. Ill let you know if it says anything in the instructions about it.

[trackfast]

Is anyone calibrating using distilled water ?

[ccCapt]

If you calibrate with distilled water, the only thing you are doing is making sure 0 is really 0. When you get to the 35 ppt mark, which is what natural seawater is at, you will be reading aprox 2 ppt lower than it really is. To calibrate it properly you should use a 35 ppt calibration fluid.
PINPOINT® Salinity Calibration Fluid - English

[sdergar]

I had this question when I first got my Sybon Refractometer. I asked the question and here is the response from them:


Dear Steve,

Thank you for purchasing Sybon’s salinity refractometer. The 0ppt ultrapurewater is suitable for calibrating our salinity refractometer for saltwater aquarium. However, you may also use the 35ppt solution. It is similar to pH meter in that it is often recommended to calibrate pH meter with pH 7, 9, or 10 solution (not cal solution of pH 4) when tested for normal seawater (average ~8.0). However, this practice is much more important in pH meter than in salinity refractometer because the difference in pH meter is much larger in pH meter than in salinity refractometer. So either 0ppt or 35ppt will give a very accurate reading for your purpose. Basically, you will not be able to see a difference on the grids by sight.


Thank you!

Kindest Regards
James – Sybon Optics Technician

[cmor1701d]

SG and Salinity are not quite the same. A SG reading of 1.026 @ 59 degrees is equivalent to 35ppt Salinity. An ATC refractometer will compensate for temperature.
On my refractometer those two measurements do line up. I'm a bit concerned that they don't in the linked refractometer, but the difference is probably not large enough to matter.

[trackfast]

Good info. Thanks to all who contributed.