Motorhome Washing with Deionizer or Water Softner

p.mcclure wrote:
We all know washing the RV is a pain. Have any of you used either a portable water softener or deionizer for the final rinse to eliminate the need to dry the thing after the wash? Does it really work to prevent the spots? Which of the two (deionizer or water softener) works best? What brand do you recommend?