Looking to start setting up an aquarium, but I'm not sure what I really want. Right now my thoughts are a 5, 10, or 20 gallon walstad with a Betta and possibly a school of panda cories. OR a 20/29 gallon shelldweller tank.

I'm sort of limited on space, but that's less of a concern than initial and long term costs, as well as easy maintenance.

I suppose if I go ahead and buy a 20 long, I'll be ready for either decision.

Question: is it possible to start off with a typical filtered tank and convert to walstad over time? Or would it have to be planned out from the very beginning? Instead of using soil and capping with sand, I think I'd prefer to start off with biostratum, or something similar that won't float to the top.