I currently have a 135, a 75, and a 65 hex running.
The 65 is kind of a catch-all community tank. I plan to convert it to fancy goldfish in the near future. It has an UG filter, an Eheim 2217, and auto water change.
The 75 is a cool-water tank with a pair of G. balzanii, Corydoras paleatus, and Bloodfin Tetras. It has an in-tank sump with a 4x16 filter sock and a Hydro V sponge, an Eheim 2217, and auto water change.
The 135 houses a bunch of G. steindachneri, six G. geayi, and six Pink-Tail Chalceus. It is plumbed to my sump under the house that runs my 210G in the living room.
I also have a 55 attached to the same sump. It is empty right now, but it that can be running at the turn of a valve.
There is a 4x2x2 fiberglass tank as well, but it is empty (and kind of buried) at the moment.