What do you wish to keep in the tank? If just softies and lower light lps, just get an 18" nova extreme. The new ones have the same sort of reflector as the nova extreme pro and at drs. foster & smith, it's $50. With the supplied legs, it will easily fit. If you want to go with sps, go with either the 20" nova extreme pro or like Jayson says, a 70w Mh.