For a 5 gal
tank, I think thats what your wanting to do. Of wich I have to say that size is highly unrecommended for a saltwater beginner. the water conditions will fluxuate alot and could cause serious stability problems.
I would get a 15W power compact florecent fixture. This would allow you to keep some low light mushrooms and leathers.
what you have to remember here is that all of these corals natural home is in the ocean around the tropics where the sun is the most intense.