Brad
Interestingly enough I have been reading alot about coral growth etc lately due to my own coral issues. Growth is directly related to food and not light. Light will keep them alive but they wont grow much. Food is where they get all of their extra energy from that allows them to grow. The most important food item seems to be zooplankton and without a sandbed you would have much less of it in your tank. Without a sandbed tho you should be able to feed the hell out of your tank without running into nutrient issues.
I dont know what to suggest for food for you, I havnt got that far yet
