Hi Stuart; I have used both cobs and ground cobs, I get the ground cobs from Pets Mart, they sell them for bedding, just plain ground cobs, no added chemicals. I used them in a Pit & Spits cooker/smoker. temp in the smoing chamber was 80-90 Deg. depending on OAT. I used a hot plate to get it started with cobs in a stainless steel bowl with small holes drilled in the bottom for drtaft.It will be a new venture with the CS 55 . ... Doug