Almost all fixtures come with crappy bulbs. Unless you buy a high end ATI or TEK fixture, bulbs will need replaced. Geisemann bulbs aren't terribly expensive,yet theyre the best IMO
. My concern is that the fixture has 5' bulbs, so you're going to have a foot of shaded area. Most 6' fixtures have 3' bulbs.
As far as the light, it will work. I kept carpeting plants with 8x24w over a 125, and a 180 is just a wider 125 IIRC. I would look at two 3' fixtures or a better 6' fixture though, if I were you. Two fishneedit 3' 4x39w fixtures hung above the tank would work well IMO