I've planted vases ranging from less than 1/4 cup of water up to 3g. All have been up and running for 6 months to a year--never had a problem with water quality in any of them outside of really stupid errors or extreme neglect.
Substrates include sand, fluorite, aquarium gravel, sand capped dirt and mixes of all of the above. Plant mass has varied from fairly minimal to fairly heavy. Water changes are pretty consistently 20-30% weekly with an occasional 2x week for bowls that have sudden snail--and thus snail poop-population booms. A few were started with an RO/tap water mix, but they've all been switched to straight tap water now.
All have some sort of snails, most have shrimp (ghost or cherries), many include endlers as well.
No filters, no heaters.