R/O unit auto shut off

[abcha0s]

I think you're over complicating this. Most ro units will shut off when a certain pressure on the clean water output is reached. Those that don't have the pressure activated solenoid built in can generally be retrofitted. In any event, I'm pretty sure the Vertex will shut off automatically once the resevoir is full.

You do need the float valve. Even if you use electronic sensors to shut off the ro unit, I would still use the float valve.