, get the largest tank you can afford...at least a 29 gal
...bigger is better. Set it up with a deep sand bed and live rock. You'll need a skimmer and some powerheads for water flow. If you want a reef tank, you'll need some high output lighting. Before you do any of this, buy a copy of "The Concientious Marine Aquarist" by Robert M. Fenner. This is almost required reading for anyone thinking about starting a SW
tank. Once you've read this book, you can start to formulate a plan for the kind and size of tank you want. Be warned that this is not a cheap hobby. But, if you do things right the first time, it won't cost you nearly as much as it has some of us. As always, we're here to help you in any way we can. You might want to browse through the articles on this site as well. Welcome to AA.com!