remove ions (dissolved) while RO
removes suspend particles.
Marty I know how you feel. I found a place that sells DI
water for $0.49 a gallon but if you get 5 gallons its only $1.49 so have not bought my own filter. You could always collect the runoff water from the RO
and use it to water plant, laundry, etc. If you don't get the RO
, you could get a two stage carbon filter 5mm and 1 mm and a DI
filter. The carbon filters will remove suspend particle (only to 1 mm) and chlorine. www.airwaterice.com
sell filters and parts to make your own, I'm sure there are other place you get them too.