Hanna Instruments HI 3221 Instruction Manual page 39

If Offset is set, after one point calibration the instrument evaluate the offset
and keep unchanged the slopes.
Custom Buffers
Focus on the Custom Buffers item.
Press Modify.
Press Delete to delete focused buffer.
Press Add to add a new buffer to the list (max 5).
Press Modify to set custom buffer value.
Use ARROW keys to change the value.
Press Accept to confirm custom buffer value or ESC to exit without saving.
pH Resolution
Focus on the pH resolution item.
Press the displayed function key to change option
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