refractometer calibration issues

[Chameleon]

so lately my refractometer has been loosing calibration very easily. I have been doing weekly water changes on my frag tank until I connect it to my display because right now it is skimmerless. each week my refractometer is pretty far off calibration reading about 1.030 on the calibration fluid. i calibrate it and the next week its off again. it didn't use to do this. any thooghts?

 

[redfishbluefish]

You have stiff hinges!

The plastic hinged cover needs to move very freely on your refractometer. With the saltwater, it quickly crudes up the hinge components of this cover. So what I do is spray a little WD40 into a small aperitif glass and then use a toothpick to dab this WD40 onto the hinge components. It takes multiple applications with working the hinge before the hinges free up and start swinging freely. You should notice that your calibration is now more stable.

 

[Chameleon]

cool ill give that a try thanks!!