Actually, a lot of pretty well known EXPERIENCED
reefers (Anthony Calfo immediately comes to mind) prefer DI
due to not just time, but the incredible waste produced from RO
water. It's somewhat like, 7 gallons waste water to 1 gallon useable water. I think it depends on your filtration which would be better for you, and also on your source water. If you only have a few contaminants, and you run a powerful skimmer and a true DSB
(5 inches or deeper) then you can get away with DI
water, no doubt. Thousands of commercial and private aquaculturists do exactly this. If however, you have a lot of heavy contaminants, RO
is the superior, if more costly and time consuming, way. And remember, your filtration is only as good as your filters. Gotta keep up on those resin changes!