I have a 60x18x24. I run 3 Kessils (2 a360s and 1 a350). I've been toying with adding a 4th one for some time but have never gotten around to it. I think you will be pretty happy with 3 a360s but you may or may not want to add supplementary light. You definitely don't need to until you've had the 360s in action for some time. I do have a black box led between 2 of the kessils this is just for extra lighting where I have some sps and I had the black box laying around not being used. While the right is slightly brighter then the left of my tank it's not that noticeable.