Biofilter performance is directly tied to media management that in turn governs both air flow and microbial activity. At start-up, biofilter media must be managed for the establishment of a robust, targeted contaminant-degrading microbial community. Media moisture content must be continuously controlled to ensure microbial community performance. The media must also be cared for to prevent compaction and pests. Throughout operation, media will ultimately degrade to the point that compaction prevents effluent from permeating and the media must be replaced. How to optimally manage media for performance and longevity are discussed in detail.