54W are almost 48" and 80W are almost 60" I have 2 54W 4 foot lamps on my 5 foot long 100g. The shadow at the ends is only apperent at the top of tank, and isn't a big deal to me. I am leaning towards two 250W metal halide lights to finish off lighting. Allowing me to run t5s for 12 hours and MH for a bit shorter duration. If you make a canopy you can add lighting as money allows. I will post update pics on my 100g start to finish thread tonight.