Apex salinity probe question

[Ziggy17]

So I decided today that I would calibrate my salinity probe as it’s been about since months. My reading prior to the calibration was 33.5 on my apex. After calibration, I’m getting a reading of 40.3. I used my manual checker, zero’d with RO water then tested the tank which read 36. Now I realize there is a margin for error but that seems to be bit too much error. Anyone else have this issue? Should I manually calibrate it to what my manual checker is saying?

 

[ReefStable Verified Sponsor]

I would recalibrate again.

Instead of zeroing with ro, can you calibrate with 35ppt fluid?

 

[Ziggy17]

I tried the auto again and it’s still off. So I did the manual and now it’s saying 31.5. The calibration fluid is supposed to be 35 ppt as per the bottle.

 

[Ziggy17]

I tried zeroing the refractometer with the 35ppt solution and the apex reading is about 5ppt off of what my manual test is saying…. What a cluster F…

 

[Frosty Latte]

Might be air bubbles on it. Try again and do your best not to have any on there during calibration

 

[Ziggy17]

Might be air bubbles on it. Try again and do your best not to have any on there during calibration

Yeah, I was super careful.

 

[Ziggy17]

Miraculously it fixed itself.