I have a couple of small rbta with a pair of small occ in a 12"cube (aqueon evolve8, but really it's about 7g with out filling to the brim) with a par38 led. They work fine for now, but its a TEMPORARY home for said fish/nem. I have several other tanks to put them in when they need more space or start stinging my corals. Or, I may just cut the nems and keep them smallish.
Water change schedule sounds fine, I would recommend using chemipure elite, and purigen as part of your filtration in your nano. If you want to plumb t into a sump, all the better, otherwise an ATO would be very helpful.