I'm going to do my first brisket and bought some chunks to use for my propane smoker ( old BBQ Grillware model from Lowes). It has a cast iron box with a slotted lid. Would it hurt for me to put the chunks in without the lid? Should I use the lid? Should I replace the lid with foil? Also, how many chunks should I use? I saw some pictures on some other threads and one by Sqwib (I believe) stood out to me. He had a box filled with chunks and no cover in a gasser. Thanks!