It is the CST10-001 so your standard 1" flow meter which according to the specs measures 0.86 GPM or more if memory serves correctly.
I agree that I would not be able to detect the “normal” flow if it is below the 0.86 GPM, but it WOULD be able to detect anything above that such as a leak (the assumption is that a leak would always exceed 0.86 GPM). It wouldn’t be able to tell you if the flow was too low but I can accept that limitation. I guess the ask would be basically to add an option under the zone calibration to allow a manual cal OR a “per zone leak threshold” that would allow you to manually specify a GPM regardless of a successful cal.
To take my scenario as an example, let’s say that the actual flow is 0.6 GPM which is below the threshold of the CST. The cal routine of course fails, it then asks me to be sure that there is some flow, and I’m presented with either the option to specify 0.6 GPM manually OR it allows me to enable leak detection by manually specifying a threshold where I would then set something like 0.9 GPM or similar.
As for my experience with the other zones, it was good. No real issues or problems at all. I had elected not to run all the zones beforehand, so I discovered that I had accidentally swapped the wires for two zones and that on another zone one of my solenoids had apparently decided to quit working over the winter. As an improvement, what would be great would be to display the instantaneous GPM as it is running and for that matter, it would be nice to see that on the Home Dashboard screen and History too. Whenever I am running while looking at the console, I always tend to want to see the inrush GPM as a zone starts up, the steady state GPM, and in the history the GPM for past runs.