I got my first smoker 2 weeks ago, and have used it each weekend since. I made my very first fatties yesterday and had trouble maintaining 225 degrees. The temp kept dropping down to 200 even with the draft wide open. Do I need to put more charcoal in the firebox each time, or do I need to do something else? I have a charbroil 1280 and was using about 2 pounds of charcoal, adding a little at a time as needed.