What to do if Hach ORBISPHERE 6110 Measuring Instruments displays W400: No message displayed?
- LlisacraigSep 23, 2025
If the Hach Measuring Instruments displays warning W400, the true CO2 may not be reliable due to CO2 purge gas purity out of specification. Check gas cylinder purity, tubing and connections to 6110 and recalibrate CO2 sensor.










