I'm in the market for a ro/di unit, but unclear which stage I should purchase from BRS. phoenix water ranges from 500-850 TDS and .9 chlorine. should a 4 stage be sufficient enough?
I would get at least a 5 stage to start with since it's not much more. From there you can always add-on another canister before the unit to reduce the chlorine a bit more. The cleaner the water is before it hits your RO Membrane and DI resin the better.
I have the 5 stage and TDS going in is only about 250, just to give you an example.