What tank is it in?
If the 55 gallon, it's probably only 22" deep. As long as the light is directly over the anemone it will be OK for the short term...I'd get another light.
What makes you think it's not doing well?
Do you have a pic that you can post?
Do you have a clown fish hosting it? You know they help with the symbiotic relationship?....
Give us all of the details on your tank...depth, number of T5's, wattage, color temp of the light, what else is in the tank, what are you feeding it?
Dave