Hey guys
I know i am popping in this discussion a little late, ….but i may have what you are looking for!
Regarding ET0 , have a look to this thread https://opensprinkler.com/forums/topic/opensensor-logger-controller-for-opensprinkler-networks/ .
Sensor Server is a SW that run on ESP8266 and can log sensor data , does local computations like ET0 and control Opensprinkler units.
This way you can have a separate unit that using Hygro Temperature sensor and a small solar panel compute ET0 based on local values or, if you prefer, on WU datas. I have a unit like that that run im my garden since last july : ET0 calculated values are correct and reliable. The unit also run an interpreter like language (bitlash derived) and , with it, you can fully customise it to control local or remote GPIO lines and/or send API commands to a OpenSprinkler unit.
Regarding Flux detection and OpenSprinkler supervision I have also started a code that read pulses from a water flow sensor mounted on the main water line. The code read from OpenSprinkler units ( it is running with 5 units now) all watering schedules and measure flow used by each zone.
This flow is checked then for all following operations to be as the one recorded; if not a warning is issued so that you can check that zone or if all zone of a OS unit are not working the OpenSprinkler itself. So with a single unit a can check watering of all units!
This flow values are also very useful for ET based valve control : it is sufficient to know the zone surface to derive the equivalent mm of rain!
This OpenSprinkler WaterManager SW will be available soon or as an addition to OpenSensor or as a separate code!