Calibrate your refractometer!!!

[hiepatitis]

I know many people assume that refractometers are accurate but they're not. After reading many articles I decided to buy calibration fluid of 35ppt (1.026 SG). I tested my refractometer and found that it read about 0.003 off. It's not enough to kill my livestock but sometimes if we aren't careful the salinity can fluctuate from evaporation or excess freshwater top-off.

I used to do a single point calibration at 0.000 SG using distilled water but apparently the slope of the measurement was off. Since the refractometer does not have a two point calibration the best thing to do was to calibrate at the nominal measurement, 1.026.

I suggest everyone using one of these things calibrate theirs.

 

[sfsuphysics]

Been there a few weeks ago, found out my refractometer actually was off by over .006 which really did make it lousy, 1.031 specific gravity or so!

It was so old that I couldn't turn the screw to calibrate it either, bought a new one, got some 35ppt solution, all is good

 

[Tumbleweed]

You guys now are making have to go out and buy some calibrating solution, and check my refractometere tomorrow

 

[alve]

I had the same thing with mine, was a big difference when calibrated with 35ppt compared to distilled water. Now I only use 35ppt to calibrate.

 

[hiepatitis]

Tumbleweed,

I have some fluid you can borrow. Where are you at?

 

[Elite]

Go to the meeting and pick one up... Norman brought 2 liters bottle of it ;D

 

[bad coffee]

I have a bunch of bottles from our fragswap. Let me know, I'll send you guys some.

B

 

[Tumbleweed]

[quote author=hiepatitis link=topic=3996.msg47582#msg47582 date=1214707912]
Tumbleweed,

I have some fluid you can borrow. Where are you at?
[/quote]
Martinez. Are you going to the BOD meeting or the Swap in August. I will be at both. Thanks