You will need lights, live rock, power heads a heater, and filtration. What type of lights depends on the type of coral you want to keep. If you are only looking to keep soft coral, power compacts will work fine, but if you want to keep hard corals, clams, and or anemone's, you will need T5's, metal halide's, or good LED's. Live rock is a must, as it provides biological filtration and sand will also help with this but is not essential. You will need at least 1 pound of rock per gallon and 1/2 to 1 pound of sand per gallon of water if you choose to put sand in your tank. You need 10-20+gph x your tank size for a reef tank, so for your tank you will need at least 400gph flow. For filtration, you can use one or all of the following: hang on the back filtration, canister filter, sump/refugium, and/or a protein skimmer. To start out, you can just purchase a cheap hob (hang on back) filter and add other filtration as your funds allow. (I actually have an Emperor 400 and an Emperor 280 for sale right now). Which brings me to my last point: the most inexpensive way to get equipment in this hobby is to buy used. There are always people on this forum, the for sale forum and craigslist who are upgrading their equipment or getting out of the hobby and selling their stuff. Also, if you cant find the size fixture you need used, you can buy a retro fit kit for relatively cheap and they are pretty easy to put together. I hope this helps. Its pretty basic, but Im sure you are already beginning to realize that this hobby requires an exorbitant amount of research. It is part of the joy of reef keeping. So, happy reading! And don't hesitate to ask us questions. Nothing is too silly to ask, we all remember when we started this hobby and no one minds answering "noob" questions here!