Very nice driftwood! Love the piece! The problem with the flood lights in depth, on a 3ft tall tank they just don't penetrate very well, my guess is you would need the larger models like the 100w flood lights to be consistently bright at the bottom. The other side to that is, if you want some shadowing and don't want a very bright tank they do a very good job for the price Another cheap option is (if the lighting is hidden or not on a show tank because its UGLY) are these:
Used with 26w cfl bulbs are actuallly brighter than those 50w flood lamps. I used 6 of those on my tank prior to the flood lamps and during the flood lamps as well (the flood lights were to dull so I removed 2 of the flood lamps and replaced with 4 of the cfl bulbs) before replacing it all with proper aquarium led lights.