THANKS!
I used the solenoid and float valve for a couple reasons. I wanted an auto shut off in case the float valve failed for some reason, and I'm paranoid enough to really want a float switch tied to the R/O unit itself so that if the solenoid fails, and the float fails, then the float switch would shut the whole system down.
I'm thinking about getting the ATO from avast. It looks nice, and has a peristaltic pump.