The first thing you need to do is decide what types of corals/inverts you would like to keep. You can then build your lighting system around that. The whole watts/gal
is a very poor way to look at things. While it can be used as a guideline, it is far from a hard and fast rule. For your tank, I would look into some form of MH
lighting with actinic CF
suppliments. The MH
will give much better light penetration (its a tall tank) and the actincs will help make the tank more pleasing to the eye. Both Coralife and Orbit make some nice MH
combo fixutes. If you are on a tighter budget, Odyssea fixtures will work (I have one) but they do come with mixed reviews.