For my 180g
1.RO/DI on the wall in garage hooked up to the water spicket outside.
2.RO/DI feeds into my 7gallon reservoir under tank.
3.Electronic solenoid hooked up inline between RO/DI and reservoir(normal state closed, so if power fails it shuts off the RO/DI).
4.Electronic solenoid hooked up on timer, only allowed to run 3 hours each morning to refill reservoir.
5.Float valve setup in reservoir to shut-off RO/DI when reservoir is full(if this fails, electronic solenoid will shut off with timer shortly after reservoir fills)
6.Auto-shutoff valve installed on RO/DI, so if float valve or solenoid is closed, backpreasure shuts down the RO/DI.
7.Kalk reactor hooked up inline between reservoir and tank.
8.Dual float switches hooked up in sump, if one sticks on, the 2nd will catch overfill and shut off top off pump.
Lots of redundancy in my system now and I'm thinking of getting the tunze osomonator to replace the dual float switches in tank, that unit has an infrared eye to sense evaporation and a float valve to catch flood, less in contact with water so no sticking on.
Keith