I use two, first one is a 30 gallon with an aqua clear hang on the back filter also two sponge filters and a small power head, and a heater when needed. This is for fish so I also use several pieces of pvc pipe.
Second one is a 29 gallon with a turbo floater skimmer, sponge filter and power head. Light is a Aquatic life 4 bulb T5, pvc rack for corals. I use water from my reef for every other day water changes. This one I use for corals, snails, or anything wet except fish.