I am starting up a 20 gallon high saltwater aquarium. It use to be a freshwater so my hood and light is the only thing staying. I want to put some corals in their but I don't know if the light is good enough. I have a 30'' Fluorescent Aquarium Reflector 20 Watt is that good for any kind of corals? I m getting any type of Low Light, Hardy, Easy Growth, Good Maintaining, Beginner.... Corals?