Refractometer help - inconsistent results

[merkmerk73]

I have a Hanna checker and lots of Hanna 35 ppt solution packets, so I've been using this, but my LFS is telling me that my salinity runs higher (1.027 to 1.026).

My readings at home and with constant calibration - I dip into the tank water and it starts at 1.027 and then falls to 1.026.

Anyway - I got a refractometer (red sea).

I can't get this thing to give me a consistent reading no matter what I do.

If I calibrate with RO water, my tank starts giving me extremely high readings. Then I try calibrating to my 35 ppt solution, and run again, and I get over 1.030 salinity.

If I calibrate with RO water, my 35ppt comes up anything but.

What the heck am I doing wrong?

 

[shwareefer]

I have a Hanna checker and lots of Hanna 35 ppt solution packets, so I've been using this, but my LFS is telling me that my salinity runs higher (1.027 to 1.026).

My readings at home and with constant calibration - I dip into the tank water and it starts at 1.027 and then falls to 1.026.

Anyway - I got a refractometer (red sea).

I can't get this thing to give me a consistent reading no matter what I do.

If I calibrate with RO water, my tank starts giving me extremely high readings. Then I try calibrating to my 35 ppt solution, and run again, and I get over 1.030 salinity.

If I calibrate with RO water, my 35ppt comes up anything but.

What the heck am I doing wrong?

I don't think you can use a standard solution designed for digital testers to calibrate a refractometer. If the redsea came with no calibration solution and says to use RO, then that's what you should do and trust the results. Otherwise you can get calibration solution specifically for refractometers if you prefer.