I never added coals after the initial chimney. I will say I used the big weber chimney and I filled it to the top and then a few. So it was a good size load of briquettes. Also I will note that the top layer of coals were not really fully lit when I poured the chimney in. I tried to dump a few of the unlit coals in each bin (I always use the weber bins) and then dumped all the fully lit coals on top....so that may have acted as a minion style fire since the bottom coals probably caught fire as the lit coals burned down.....if that makes sense.