I'd say that you could probably keep anything except SPS and clams. Certain LPS you might want to keep higher in the tank. Though I should point out that if you are interested in 48" T5 lights, you should look into something with individual reflectors. If you're willing to set up a retrofit, you could buy a setup of 4 48" T5s for just a little bit more than the Nova. Having the individual reflectors drastically increases the the amount of light that enters the tank.