Nice fixture.
I had a 8x54W dimmable T5 as well and saw the lamps wearing down quickly when not using them at 100%.
IMHO, if you go the T5 route, you want to have them blast the corals with as much PAR and spectrum as possible. I am not sure if anybody ever tested this, but the spectrum of a T5 at 50% is not the same as at 100%. The lamps run at lower amps ad the gas inside is not burned at the optimal point.
In your case, using all the same T5's, you can just shut off 1 pair to have the system work at 50%.
Your tank looks great by the way.
I had a 8x54W dimmable T5 as well and saw the lamps wearing down quickly when not using them at 100%.
IMHO, if you go the T5 route, you want to have them blast the corals with as much PAR and spectrum as possible. I am not sure if anybody ever tested this, but the spectrum of a T5 at 50% is not the same as at 100%. The lamps run at lower amps ad the gas inside is not burned at the optimal point.
In your case, using all the same T5's, you can just shut off 1 pair to have the system work at 50%.
Your tank looks great by the way.