TC-3000 Meter Troubleshooting Guide
The 2020e and 2020i turbidity meters will display negative results if the sample water is less turbid than the blank reading. This is possible in ultra- low turbidity waters, where the sample turbidity is at or near the detection limit of the meter.
Negative readings can also indicate a problem when the meter was blanked. If the meter is accidentally blanked to a 1.0NTU standard, subsequent tests may negative, in response to the high blank reading. Correct this problem as follows:
- Reset the meter to the factory calibration settings: with the meter turned OFF, hold down the *OK button and press ON. Release both buttons at the same time. Press *OK to select the default settings. Press *OK again and the meter will turn off. The factory settings will be restored.