Those tanks Do look pretty sweet. I'd be more inclined to jump on a MR. Aqua 12, for more volume and rimless, but that is going to set you back much more than the bookshelf.
If you went with an inert black sand and some almond leaves or alder cones for tannins, you could manage CRS. Probably plan on re-mineralizing RO. I'd start with low grade CRS-And no more than 10 until your confident you can keep them alive for a few months.