Refractometer question

[jeff2516]

So I purchased a ATC (automatic temperature compensating) refractometer and fluid, and right out of the box got a reading of 1.026 when using the fluid. A week later I tested the refractometer with the same fluid and got a reading of 1.028 and had to recalibrate to 1.026. Is it normal to have to recalibrate a refractometer before each use (assuming the screw was not adjusted)?

 

[navila06]

I am new to refractometers, the one I purchased uses distilled or rodi water to calibrate, I recalibrate it every other time I test, but seems it never needed it yet. I have had it for 4 months now.

 

[Usctom]

I had one that need to be constantly adjusted. If the room temperature has changed it may have changed. My new one I haven't had to adjust since the first time.
Is it a cheaper model or name brand?

 

[navila06]

I bought this cheap one, works great so far.

Saltwater Aquarium Salinity & Specific Gravity Testing: Portable Refractometer

 

[Reefing Madness]

I bought this cheap one, works great so far.

Saltwater Aquarium Salinity & Specific Gravity Testing: Portable Refractometer

I bought this same one 10 years ago, been using it ever since, and only have to calibrate it once in awhile.

 

[navila06]

I'm glad to learn I am going to get many years out of it.

I bought this same one 10 years ago, been using it ever since, and only have to calibrate it once in awhile.