While you are correct that Java ferns do not need a planting type substrate, they also do MUCH better if you dont burry their rhizome (the area that the roots and leaves grows from that looks like a green branch). Java Ferns do much better when attached to a piece of wood or a rock. They WILL grow with the rhizome buried, but not as well.
A nano hob is a very small hang on back filter, like the AZOO palm filter. They are great little HOB filters. For a tank with all slow growers you dont need a super high concentration of Co2 so they will do just fine.
yeah the one java fern is attached to the wood as you can see. i have one that grew like CRAZY in my 10, at least 1.5-2 times as big as when i got it now that i attempted to bury, though i may not have, which might explain its growth.
any suggestions for a good nano filter?