I have a DI tank that I use to wash and rinse, once I am done with the “Final” rinse I use a battery powered leaf blower just to knock off the bigger beads of water and that’s it… I got tired of fighting water spots and bought a 1/2cuft dI resin tank and it is worth every penny. At 170 tds tap water a tank lasts roughly 3 months at a wash per week and I use it from start to finish, not specifically for a final spot free rinse but Pre-Rinse, wash and final. Water spots are a vehicle’s equivalent to having herpes