I sealed the bottom and top vent. I used BGE gasket material to seal the bottom vent and high temp rtv for the top. Some folks say the kamado cooking environment is moist enough, but I have had grat results with the water pan and I think it helps control the temps for a while. There is a lot of info on the acorn on JM Setzlers kamado guru site. Not to take anything away from this site of course.
Ducane. Chargriller Kamado.