I am currently running a mini reef in a 2.5 gallon, and one in a 20 gallon.... just make sure you have about 2 1/2 watts of lighting per gallon, and about 20gph per gallon of water for flow. Use livesand, liverock, and a Specific Gravity of around 1.025 if you're going to introduce corals. Cycle the tank with the sand and rock, should take anywhere from 2-4 weeks to finish your cycle with this. Oh, you want to have 1-1.5 lbs per gallon of sand, and the same with the rock. If you have any more questions... just let me know
