Are you wanting to use salt water in your ATO or are you taking about using the water you buy for your ATO to mix the salt? What water are you using for your ATO? If you're buying RODI from a LFS they probably sell premixed water for $.50 or$1.00 more a gallon. It might be easier now to just buy the premixed for water changes right now. Worry about mixing it yourself once you have a RODI unit.I was thinking that I could just mix my ATO with salt mix and call it the day.