Pellets will swell as they absorb moisture either during a smoke or from less than adequate storage. Try just chips which are dryer from the outset. Small chips. If you are wanting to use pellets, keep them in an airtight container. Also, make sure to clean the bella per the instructions after each use. Keep the air pump at max flow for 10 or more minutes to ensure you have a good burn going as per the instructions. Also, the humidity in the air where you live will be drawn in during use. Tinker with it till you get what you want.