Tech note
The U26-001 DO Logger and Sodium Sulfite Solution U26-CAL-SOL

After performing the optional 0% saturation lab calibration step (step #2) with the sodium sulfite solution ( Onset part number U26-CAL-SOL), be sure to soak and thoroughly rinse the sensor cap with fresh water prior to deployment. If possible, allow the sensor cap-end of the logger to soak in fresh water overnight and then rinse again with fresh water to ensure that no sodium sulfite residue remains prior to deployment.