You usually don't need anything over 3-3.5 wpg
. Granted, this setup is going to save you about 20.00 + the cost of a hood/ building a canopy, but don't you think it'd look a little funny having 2 36' fixtures on a tank that is probably (i'm just guessing here) 48' long? Either you'd have a 6' gap on both sides if you put your lights behind one another or if you put one at one end, and one at the other, they will look offset to each other. I guess its all in what you fancy, and how much cash you are going to spend. Just a little bit of a forewarning tho. If you're thinking about having a planted tank that looks like one of these: Link
Its going to cost you alot of money and time. You're going to have to get a GOOD substrate medium, (flourite is what I use), good lighting, frequent plant trimmings, pwc
, dosing ferts, co2
, schedule schedule schedule! It will be worth it in the long run, however you shouldn't skimp on your parts or make it not look as good as it could. A build canopy would make the tank look extremely nice, make sure to research everything before you dive right in. You'll want to have an idea of what kind of plants you want, then put the substrate it, plant them when you have about 1 or 2 inches of water above your gravel line then gently fill the water, etc. Its a big time consumer like I said, but definitely worth it. If you have any further questions, feel free to pm me.
Ps. I don't want you to think i'm plugging that much for the ah supply kits, but i've seen them in custom canopy of my friends, and its real bright and makes for a wonderful display.