Lots of ways do do lighting. I agree with TeenReefer, its personal taste. If you want to fill the whole tank with light, get an 8 bulb, if you set it up with a very thin line of rock, you might be able to get a 4 bulb to work (not the best idea imo, but could work). 6 bulb would be the fewest I would go personally. The other thing to consider with t5's is that the more bulbs you have, the more you can mix them, two bulbs in one spectrum, 1 bulb in another, three in actinic one fiji purple, etc... and the more bulbs you have, the more they cost... Everyone in this hobby has opinions about lighting, and they can all be right, just not right for you... Look at some different reefs, look at some different light setups, find out what coral you want to keep, because you don't need the best lights ever made if your going to keep a tank of leathers, and gorgs.