What to do if the red indicator light flashes on my Hach Controller?
- GgreenemarkSep 5, 2025
The red indicator light flashes when one or more measurements that the sampler is configured to use (such as pH and flow) are unavailable because the corresponding sensor(s) isn't connected. To resolve this, connect the missing sensor to the sampler. Also, verify that the sampler isn't configured to record unavailable sensor measurements to the data log or set up with alarms for sensor measurements that are not available.






