[El Exorcisto]

I have 4 bulbs, each one overdriven 2x over my 55. I'm running two 6500K Phillips Daylights and two 5000K GE Sunshines. The light is intense enough to start my hygro difformis and val. americana pearling in under five minutes. I never really worry about the actual intensity when I see results like that so quickly. Halides may be more intense and have that sweet shimmer going on, T5s may be ultra-efficient, but you can't beat overdriven T8s for initial and maintenance costs over a 4' tank.

 

[El Exorcisto]

I have my strips sitting on my tank, no canopy, just a couple sticks as intermediates. Pearling is caused by plants photosynthesizing fast enough to saturate the water around them with oxygen, causing oxygen bubbles (not air) to form under or between their leaves. If you have a 55, use two strips if you want the maximum amount of light... The tank can handle the footprint. You need CO2 if you want high lighting. Everything needs to be balanced, and you are out of balance if you are not running CO2 with high lighting levels. Homebrew CO2 is cute on a 10 gallon, but it gets old on a 55, trust me, I know. I have a Red Sea Paintball system and love it. Do yourself a favor and spend the coin on a cheap pressure system as soon as you can.