Bought my BGR large yesterday. Tried 3 racks of pork babyback spare ribs. Most recipes called for temp 225 for about a total of 1 hour. Actually cooked them for 2.5 hours using indirect with a drip pan filled with water. They did not appear done. Used thermometer, which showed temp 115. How do I know when they are done? I am used to cooking on a gas grill. Thanks in advance.