We recommend updating the ISUS or SUNA's reference spectrum portion of the calibration with the instrument in the same state it will be used in the field. To update the reference spectrum, you will have to run the calibration feature in ISUSCom or UCI using a pure water sample.
For best results, we recommend the following:
1. For profiling situations, when the instrument will be run for extended times, the reference spectrum should be updated after the sensor has been run for several minutes. This will allow the Nitrate reading to stabilize.
2. For moored applications, we recommend that the instrument only be run for a short duration to collect the pure water data during the calibration. Data collection in the field should only have the instrument run for 20 seconds per acquisition.