If you have live plants, and need to have lighting for them, as well, you could use a dual Arcadia fixture. It comes with 6.5 bulbs standard, and you could upgrade one to a 6% T5 HO bulb. This is what I would suggest. 12% would probably be overkill. With the reflector in the Arcadia units, you should get great output. Shoot Todd at LYR a message with your cage specs and he is a great help!