I don't think that is bright enough for that depth of a tank. I have 4X54 T5 HO on my 72G which is only 22" tall, and with 2 bulbs on, it looks okay, so I think you are going to need at least 6 bulbs to make the tank look nice and bright unless, you want the dim, amazonian blackwater type lighting.
I might do more lighting, I will just have to play with it a little. But without live plants, excess light just means more algae and diatoms from the silica sand.
Well I guess you're right on that one, so I will say because I don't want Cyanobacteria lol. Especially on an acrylic tank, they are hard to scrape off of glass so acrylic seems worse.