The majority of our stand-alone models will feature our filter status indicator light that will be lit when the filter requires maintenance. With this in mind, it is important to habitually clean your filter to ensure proper airflow. It is good form to clean your dust tray; depending on the volume of skates you are sharpening, you may want to consider cleaning it daily or weekly. We recommend that you tap out your filter to rid it of excess debris. Be careful not to wet the filter as it is coated with a flame retardant that is soluble. When you have noticed that cleaning the filter is no longer helping and the exhaust has diminished in suction, it is time to change your filter.