I currently have a 10 gallon tank. My filter is a Fluval 30 and I have an air pump to produce bubbles from a bubble wand. It's been up and running for a couple of months.
My tank occupants at the moment: 6 Neon Tetras, 1 Dalmatian Molly - female, 1 Fancy Tailed Guppy - male, and a Mystery...