I need charcoal recommendations. I am using a vertical 2 door Brinkmann charcoal smoker and in 11.5 hrs I went through almost a full bag of Kingsford Original ( blue and white bag ). I was adding 4-5 briquettes every 30-40 min. to keep the temp at 235. I was very happy to get it to hold and stabilize at that temp, but not happy with opening the bottom door every 30 min. I have read here elsewhere that people get a "3 hr" burn time before re-stocking the coals. Any ideas or suggestions/ methods on how to do better?