W. Eder developed a circuit for Section control, based on the Arduino Nano. It will fit for the most needs. It supports 7 Sections, 1 Flowrate regulation, section switches, AUTO/MAN switch, Main on/off and pressure/flowrate switch. You can easily change it for 2 flowrates by only using 5 sections… The relays for the sections an 2 pole changer, so every case like: spray on +, off on +, or on:+/- off:-/+ is possible.
It is only for testing, no guarantee, that it will work. Build it on your own risk.