Am I doing this wrong?

[PSU4ME]

I have a new apex with the “lab grade” salinity probe. I did the initial calibration and it seemed fine. I’ve got an ato so unless I do something, it should read consistent. So looking today, I saw it jump:

So I got out new fluid, did the automatic calibration in Apex and now it shows this:

What gives? Brs refractometer calibrated with 1.026 fluid shows 1.025. I know they are diff test but dang, why the heck is it so far off?

 

[Billldg]

Air bubbles and micro air bubbles can cause issues with the probe, sometimes you can just swish the probe around in the water gently to cause it to go back to normal. I also dip the whole probe in the sump and tilt it upward to make sure any bubbles can escape.

 

[PSU4ME]

I have that a shot, no dice!