Been a long while since I lurked onto here!
Just last night I built a new setup for turning off my RO/DI
I used an irrigation valve (12v), a standard electric float switch, 12v/15a relay, 12v wall wart, and a 'hang on tank' pump mount that came with a rio pump at some point in time. Only trouble was buying the proper sized bushing to reduce the 3/4" irrigation valve down to 1/4" fittings.
If you want some pics of my setup to better understand, just ask
