I have a char broil that I modified into a reverse flow, you can see it here. http://imgur.com/a/yn30D
Right now, I generally light a full chimney and put it in the box to get things started.I then just add charcoal as needed on top. However, whenever I do this, it seems to drop the temp by 20 or 30 degrees. Should I be lighting charcoal in my chimney each time I add it, or is this really just a temp drop from opening the firebox?