You could probably remove a few bulbs and lower your fixture If you wanted to save on your bulb life, and electricity! If you calculate it right, you could even keep your Par the same.(Par=micromols per square cm per second) Or you could lower your light levels towards the low side, saving you time spent with your arms in the tank trimming plants, co2 and money in the long run.
Thanks for the advise. was thinking of doin that but i like the way it grows although your right my hand is in the tank at least once a week trimming. 2 of the bulbs are blue coralife ones ( i like the colour ). The T5's dont really chew much power and i dont pay for C02 (i work for a welding suppyls company) so might leave it how it is, until i get sick of pruning it.