Driving myself nuts...

[MnFish1]

I thought about this a bit - Im not sure which brand - but 2 fixtures that would cover the area that's not underneath the brace would seem to be the best option (i.e. if you've seem some of those fixtures that are large and square - if you hung 2 of them above the open water it might be best. When I've had a brace like that - it always reflected up - and it annoyed me lol. - again just personal preference. you could do 4 radions oriented perpendicular to the long side of the tank - but the tank is a bit narrow - I don't know how that would look. For me - just giving you something to think about - I dont like room spread - I just want to see the light on the tank - not in the room.

 

[saltyfilmfolks]

Basics.

3 on a 55.
As close as you can get to t5 coverage.

 

[MrObscura]

Primes would be fine for width and depth, especially with higher light corals kept in the top half, but length would be an issue. I'd want one for every 12 inches so you'd need 6.

Though since lighting a big tank can be so expensive it still might be the cheapest route as far as name brand leds.