I have a 120 gallon 48x24x24 with 2 400 watt MH and 2 110 watt uri actinics. I was usuing 6500k Iwasaki's but switched to 10000k Ushio last a few days ago. I like the color a whole lot better but It has not been long enough to tell anything about the growth rate. I don't plan on fragging it until it gets bigger and intrudes on other corals. I would say that it was about 2.5 to 3 inches when I got it and know it is about 7 inches in diameter.