how to use new refractometer?

[sjfishguy]

I am not as much of an idiot as the title seems. After holding out for a while (dont ask why), I finally got a refractometer. Do you guys calibrate it everytime you use it? Do you wait for the water to cool to the temp of the refractometer crystal? I calibrated and tested my water the first day and it read 1.031 (my swing are said it was 1.025....... I know, I know). Anyway I have been lowering the salinity slowly, constantly monitoring the salinity. I just put some distilled water in my refractometer and it read above 1.00. So I recalibrated it and have proceeded from there? Should the calibration have changed in a matter of two weeks? Is this normal?

 

[minimalist]

I've had mine for 60 days. I have used it ~15 times. Came in perfectly calibrated and remains that way to this day.

 

[Agu]

Mine seems to stay in calibration...


However I've found that often i don't clean the lens and cover well enough between uses. Often first check will be off more than I expected so I'll clean and retest. The second check is usually more accurate.

Guess what I'm saying is that it could be user error if your refractometer goes out of calibration often.


fwiw,

 

[cchoffman]

If you don't bang it around a lot, and clean it good, it will stay calibrated for a while. It is still safe to check it now and again.

 

[squirmy]

my refracto read 1.003 with RO/DI water. I then tested it with the calibration solution described by Randy Holmes Farley (coke bottle and table salt). i ensured the temp of the solution and room were 68 and calibrated. My refract still reads above zero with RO/DI, but is an exact match with the solution.