Four of my tanks are on open stands, so there's nothing under them except canisters. The fifth one is is on a cabinet, and you don't want to see inside there! Lol. I keep all my spare hardware, decor, and the bulk containers of nls food under there.
All my other gear is on trolleys, and in crates. Oh yeah, and spare light fixtures, tubes and plumbing in the garage. Darned hobby has taken over my entire house!