Alan Fisher of Fisher Air in Brea, California submitted this photo of the month of a Five Filter “Bank” taken by his son Scott on a recent service call. He opened the filter access door on this upflow unit and discovered their customer had been hoarding filters. In an attempt to increase filtration efficiency, can you imagine the effect on effect these five filters had on the CSER of this system? What would you imagine the pressure drop over these five filters to be at 2000 CFM?