I'm thinking this is related to the coral question in the other thread?
I don't think you're going to like the answer to your question, but I'm pretty sure that the only way you'll be able to increase the lighting on that tank is to ditch the top part and find a fixture that will fit across the width of the open tank. The ballast that's built in to that top most likely can't handle much more wattage than what they ship it with. (Just guessing here though... maybe someone that has this unit can fill in better details.) In reality, all that biofilter stuff in the top isn't needed anyway, if you have enough live rock. And I think you do, if I remember right.
I originally was looking at those Eclipse units when I started thinking about a saltwater tank, but then realized that they just don't lend themselves well to saltwater, let alone a reef tank.