Is the Aqua Safe brand a good brand? I am looking at a Aqua Safe 75gpd Reverse Osmosis water filter. Its on ---- for $89.00 it comes with a good warranty and extra filters.
RO removes impurities...the DI portion removes ions...positive, negative or both (depending on the resins).
Email those people and ask if they can add the DI on for you. Most of those places are very willing to help you.