It's a reef tank so I'm assuming that you want corals... but what type of corals do you want? SPS, LPS, Softie? Each type of coral demands different water conditions and lighting. I'm just assuming that you want something just to start out with so that you can mildly get addicted to the hobby without breaking the back - while at the same time the equipment you buy now will also advance you from a novice position to a more amateur approach to the hobby. For that, here's a quick list of equipment and other few odds and ends that will help you get started on a budget.
For a 55g saltwater tank, assuming that it is not drilled for an overflow box and you will not have a sump:
4' nova extreme T5 HO lights with individual reflectors - yes, it's a little on the expensive side, but you will not regret the purchase. lighting is one of the most important purchases you can make for your tank.
An octopus protein skimmer or a Coralife Super Skimmer will both work well for someone on a budget. I personally buy a protein skimmer that is rated for twice the amount of water that I am setting the tank up for. If you have a bigger budget - you can always go the Deltec, Tunze or BubbleKing route with your equipment - but those kind of prices are out of my league. A protein skimmer is perhaps your second best investment when it comes to the hobby. (and yes, I know, for those of you out there that know me for my love of refugiums, this is hard to swallow.) Make sure you purchase a protein skimmer that comes in a Hang On Back version (HOB)
You will also need some sort of heavy filtration which you can easily customize. I recommend the Emperor 400 biowheel filter. It is efficient, and has never given me any problems - and if it does, you just clean it right up and buy a new impellar. Cheaper to run over time then other filters. (of course, I know that's just my honest opinion.)
You will also need a heater to help regulate your tanks temperature. Any titanium heater would do. I would personally stay away from glass heaters because they could break easier if a rock falls on them. (IE Electrocute not only your corals and fish, but perhaps yourself!)
Another great investment before starting your tank is a GFCI unit that you replace your regular outlet with, and power strips that also have built in GFCI units or breakers. Make sure you loop all of your cords to prevent water from following your power lines and perhaps dripping into the powerstrip. If that happens, your GFCI will cut the electricity so you can fix it - but still, it's a good precaution.
For a 55g reef tank, you should have a minimum of 60 pounds of live sand (or 60 pounds dry based Oolite Aragonite) I don't believe that live sand is actually live when you buy it at the store. Also, you will need a minimum of 60 pounds of live rock. Caribbean live rock is perhaps the cheapest, but Marshall Island and Fiji live rock is some of the best.
Other then that, read the FAQs on this website and...
WELCOME! Enjoy your stay.
