OK, I'm probably an idiot, but I need help! I bought a regular Weber charcoal grill, big green egg charcoal, and a charcoal chimney. I get everything started fine. How do I keep the coals going? I get barely 30 minutes of heat out of it. Do I add more charcoal (not brikets)? How do I do that after the food is cooking? I would really appreciate help with suggestions. Thanks.