What items do you need for a saltwater aquarium?

You would need as large an aquarium as possible and the following gear to suit the size of tank and stand. A Protein skimmer, a Power filter, an Ozonizer, live rock, live sand/gravel a Hydrometer, Thermometer, Lights. (Maybe a refridgeration unit). A complete water testing kit. A good book of instructions and if possible an exerienced cold water marine aquarist to help you.