Unicel 2 C-7699 Spa Replacement Cartridge Filters 100 GPM Pac-Fab Wet Institute Industry's most complete line of replacement filter elements Pentair Pool Prod (R173300) Pentair Pool Prod Pac Fab Replacements (17 2812) Pentair Pool Prod Pac Fab Replacements (17 4985) Wet Institute (32050204) (Note: Three 105 sq.ft. cartridges required.)