Embodiments of the present invention pertain to reducing the obstruction of air flow through a bypass channel associated with a disk drive. According to one embodiment, disk drive filtering system includes a selective filtering region, a pass-by filter, and a filter free region. The selective filtering region is disposed within a bypass channel. The pass-by filter is disposed within the selective filtering region and is used for filtering a first portion of the air that flows through the selective filtering region. The filter free region is disposed proximate to the pass-by filter. A second portion of the air is allowed to flow substantially unobstructed through the selective filtering region.