To determine a ‘dark count’ value or ‘offset’ for your ECO we recommend that the instrument be configured in as close a manner to the actual deployment mode as possible. This means the meter should be installed on the cage or logging system (CTD or other data logger), powered and deployed in water as it will be during operation.
To check the dark count yourself, follow these steps:
1) Cover the LED and Detector with black electrical tape or a black
static cling sticker and turn the system on.
2) Record the ECO’s output. Use the minimum or average value as your offset.
WET Labs records sixty seconds of data at 1 Hz and reports the minimum value on the
calibration worksheet.
Variability of 1 to 2 counts is expected behavior, but if you encounter variability of more than 10 counts, or if your offset value is greater than 20 counts off of the value on your Characterization sheet, please contact Sea-Bird Technical Support.