John Hakim's 5.5g Reef Tank with its amazing collection of Toadstool Leather Mushroom, Xenia, Zoanthid, Finger Leather, Green Fluorescent Mushroom, Blue & Red Mushroom, Ricordea Mushroom, Christmas Tree, Carnation Tree, Red Sea Fan, Yellow Polyp and Frogspawn corals, plus a myriad of critters.
Smaller tanks make great Do It Yourself (DIY) Projects. They are fun, easy, inexpensive and go together quickly. Just modify the DIY 55g Glass Aquarium Plans to meet your needs. There are a number of Canister and Power Filters and Mini/Nano Reef Tank Lights which will allow you to keep corals in your new tank.