Hey Shawn! I have a 40b with a 36" bml regular dutch light. I've only had it up and running for a few days, but it seems like plenty of light. I have mine mounted right on the tank. If you were going to hang, then maybe go with the xb. I don't know how soon you are looking to buy the light. If you're patient, you can follow the thread in my sig and make a more informed purchase.