I built a large water-cooled system 2 years ago and purchased both the Flow Meter and a Delta 1000 pressure sensor. But, I messed-up and used a 1-bay square tank that is not really a "water column" so the pressure sensor did not go in. This sensor has 1 port, so it's a fill-level indicator I guess.

Yesterday I added a large external EKWB reservoir and installed the Delta 1000 on the bottom. Had to update the firmware then it had all the configuration options. However, I've only seen it bump-up from 0 to 1 a little. So I am guessing it is because this sensor is way too "strong" and won't sense very small pressure variations. It seems this combination was a mistake.

It that accurate? At this point the choice is to replace the Delta 1000 with something like a Delta 40, correct? And it would probably work better as a differential sensor I would think.

Thanks for your time and input.

Yes, that's why it did not go in until I added an EKWB 354mm tube above everything else. The sensor is mounted on the botton of that. With the 1000 it moves from 0.0 to about 0.3.