If it is just soft corals your wanting to grow, and possibly low light LPS corals like Acans and Chalices, then if you could lower your light from 10" down to say 4" above the water and not use any optics at all you could get by without going with so many LEDs. The problems come when you add optics, it really adds a lot more light to the tank, too much at times, and causes color banding in the water, which is why you need to raise the light up a lot higher than normal or add more LEDs to not have the color banding. Unfortunately, 10" up without optics, it isn't going to give you much light at the bottom of a 30" tank, but 10" up with any optics tighter than 80degrees is going to give you color bars and more than likely give you way to much light in certain spots in the tank.