Refratometer Calibration Help

A

afishfanatic

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I read a couple of other threads on how to calibrate a refratometer. So I bought some of the 53.0ms conductivity solution and attempted to correct mine. On my refractometer it has 2 scales: one for d20/20 on the left and one for 0/00 on the right. I am assuming that the 0/00 is the same as PPT?
 
When you test your water does the one on the right show somewhere around 35? If so, then I'd think that's ppt. (assuming your water is close to 1.0264 / 35ppt to begin with.)
 
The problem I am having is that when I use the 53.0ms conductivity solution to calibrate my refractometer to 35, my tank reads 1.031 after I test it. Today I went and borrowed a refractometer from a friend and had the exact same result. Could it be bad testing solution?
 
I had forgotten to mention that before calibration, both refractometers read 1.025 when testing my tank water. Also I used a hydrometer ( I know not that accurate) and it read 1.023.
 
Is this the pinpoint solution from PA? That's the only one I know that has the same refractive index as 35ppt seawater.
 
Here is the package of the solution I used. Scott it did come from Premium.

Rick - When I calibrate it to 35 with the calibration fluid, Ro water tests at 10 and my tank tests at 45. Everything seems to be 10 ponts off.
 
Sounds to me like the calibration fluid is off. If it does not read zero with distilled water I would not trust that reading. Unfortunately I do not trust those calibration fluids all that much. With such a tiny bottle, a minute amount of evaporation in the fluid would throw the salinity reading way off. And who knows how old it is.
By the way Dean that fluid is used to calibrate a conductivity meter.
For a refractometer I believe you need a different solution.
Take a look at this article.
http://www.reefkeeping.com/issues/2004-06/rhf/index.php
 
Rick - In that article I found this:

Ron Shimek has discussed salinity on natural reefs in a previous article. His recommendation, and mine as well, is to maintain salinity at a natural level. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than S=35 may make good sense. Otherwise, I suggest targeting a salinity of S=35 (specific gravity = 1.0264; conductivity = 53 mS/cm ).


I think you are right about the solution being bad. I will have to look for another alternative.
 
You're both right.. 53.0uS/cm is the proper conductivity of NSW, and the pinpoint fluid also has a known refractive index that is the same as NSW.

My guess is this neptune fluid has a conductivity of 53uS/cm but a different refractive index. I'd calibrate with RO, and go with that until the next meeting when I'll have the pinpoint fluid with me and I can check it.
 
Hey guys, another calibration question if you don't mind........

I just realized that my salinity has been off, because my screw has slowly moved when I handle my refractometer ( I'm going to put some of the wifey's nail polish to seal the threads ) and I need to slowly bring it back up ( i'm just going to top off with salt water until fixed )

What I would like to know, is if my room temp is at 78 *F, and it is suppose to be calibrated at 68 *F, how much of a difference will there be with the ATC ( auto temp control ) units?

Or should I not worry about it and just check the water at tank temp?

Thanks
Stan-O
 
ATC is to account for it accurately when the unit is calibrated at 68*. I threw the refractometer in the fridge for a bit and tried it again, it was only off by 1/2 a line, so I put some of the wife's nail polish on the thread to lock them, that should do the trick.

Stan
 
@Ashlar wrote:
My guess is this neptune fluid has a conductivity of 53uS/cm but a different refractive index. said:
Scott, I think you are right. Nicki has some of the pinpoint fluid and it was 10 points different that the Neptune. :shock:
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