My shallow reef is 4'L x 2'W x 14"D and I had 2 OceanRevive T247 fixtures. I recently got a hardly used ReefRadiance Lumentek Pro which is 32 " long and it does a good job as well. I just got a good deal and I like the sunrise/sunset ability over just on/off timers of the T247. BTW, mine has a very mixed and changing complement of corals, fish and critters. The prize of the tank is the 20 very colorful and fluorescent rock flower anemones.