I'd recommend doing some research on the DSB. There is a lot of information out there pointing toward the DSB being a great sink for nutrients until it is full, then it becomes a major issue to remove it.
If this is your first reef, I would suggest either going with softies to get a feel for it, or slowly adding SPS and monitoring how they do. They are a lot more sensitive to consistent, very high quality water parameters and are not very forgiving.
Plan very carefully. If you are going to keep SPS, plan your flow accordingly. Also, as Brad stated, with a 24" depth you will need high intensity lighting if you want to keep any light loving creatures lower than the top of the rockwork. Plan out where you will place your rock and look at how the flow will work with your plan. Clams love light. If you are going that route, plan for 250W DE or 400W MH light Brad said. Otherwise you will be battling to maintain them.
Start clean; Get an RO/DI unit to ensure you are putting clean water into the system. Get a good set of test kits (salifert is a fine brand) for Alkalinity, PH, Nitrates, and Calcium (if you are keeping anything other than just softies). Get a refractometer. Plan how you are going to maintain your equipment before putting it together. That way you will think about how you will remove items and make it easier on yourself in the long run.
Lots of reading and join the local club. Real people to talk to and look at their tanks is a highly valuable resource.
Plan your fish and understand their habits and adult size before introducing them. It's much easier to not put a fish in than to try to remove it.
Keep asking questions and doing research.
the dimensions on it are 48x18x24.
