Dear Zee,
The irrigation amount (CCF) is just an estimation. Netro knows how much time your garden has been watered, but doesn't know how large is your area. By default, Netro set the zone area as 1000 square feet, which could be much higher. If you want accurate estimation, please update the zone area in settings -> zones -> area
Yes it does not detect the water flow. Thank you and I will forward your request to our R&D.
Thanks,
Netro Support