Just one bucket? Have you done any testing to make sure the CO concentration is high enough, like near 10,000 PPM, which would require a CO meter that can measure to that level? CO, which will most likely be my method, unless something changes for the better in acquiring N, is nothing to mess with as far as not having it exactly right. If the level doesn't reach high enough, you can permanently hurt yourself instead of, actually, killing yourself. When I get to the point of ctb, I plan several trial runs of placing at least 3 buckets of coals in a tent and measuring the level of CO each time, so that I can have confidence in a level high enough to make me unconscious within seconds, followed by death shortly thereafter. I don't know how one can be sure of this method without actually doing testing. I'd be worried only using one bucket of charcoal. In the case of CO, more is better.