I do now use RO on my "SPS attempt" tank. I switched to RO exclusively on it ... oh, about maybe two months now? (I'll have to check my log to be sure, but it's about that.)
I don't have DI though. Would like to, but ... then I have to get a what, a TDS meter and replacement resins and ... oh man I can't keep up with all the stuff I need. :shock:
One day...