Refractometers and Salinity Measurement

[Boomer]

http://reefkeeping.com/issues/2006-12/rhf/index.php

Note;

We have had countless reefers test their refracts using a std. Many but not all are right on using the std and need no re-calibration.

Someone make this a sticky

 

[blue_eyes53813]

lol some looooooonnnnnnnngggg good reading boomer

 

[Woodstock]

*stickied*

Excellent! I can't wait to read this after work....................

 

[Boomer]

error in article

A new standard for hyposalinity can also be made by mixing two parts 35 ppt seawater and one part freshwater

Nope, should be one part 35 ppt and 2 parts FW

(1.026 +1.0 + 1.0) / 3 = 1.009 or 12 ppt (hypo)

(1.026 + 1.026 + 1.0 0 / 3 = 1.017 or 23 ppt

 

[Woodstock]

Thanks Boomer

 

[Boomer]

Randy will have the error fixed shrotly

 

[lgerold]

Excellent reading!

 

[DrHank]

Sorry that I wasn't able to respond sooner Melanie. Steve's post sums it up. There are many calibration solutions on the market. The point though is to calibrate any refractometer as nearly as possible to 35ppm at the optimal temperature. Slight inaccuracy would rarely cause any problem because there are natural fluctuations that occur. The time that accuracy really becomes a major factor is with hyposalinity treatment.

Also, I don't use any calibration solution. My 30 year old bulb hydrometer still works great so I haven't found the need to purchase a refractometer. I have used refractometers many times but my old hydrometer is even easier to read and consistently nearly as accurate.

 

[tbittner]

I've shelved my refractometer in favor for my new Pinpoint Salinity monitor. Hands down, without a doubt, it's much more acurate and just easier to use.

Don't get me wrong, the refractometer is VERY easy to use, but it just doesn't get any simpler then "Put the probe in the water, swirl it a little bit, let it sit for a couple minutes, compare the number to the chart to get the SG". And it measures SG down to x.xxxx and it's incredibly acurate.

And with my not so good eyes anymore, the LCD is very easy to read. I don't even need to go get my glasses.