Since you are building your hood, I would go with more lower wattage bulbs so you can space them out well and get full coverage. Those dark spots can really promote algae growth.White paint sounds fine. Cheap and easy. So I have a question about wattage now. Would it be better to go with fewer, higher watt bulbs, or more, lower watt bulbs? I'm really torn. Will one way create more heat than the other?
You really should think about installing some fans with that amount. Installing fans would be easy with your setup...2 in and 2 out.Bored, I that makes sense. I thinking either 24 total of either 14 or 18 watters