4) Unicel C-7483 Spa Replacement Filter Cartridges 81 Sq Ft Hayward Swim Clear Industry's most complete line of replacement filter elements Hayward Pool Products (CX580XRE) (Note: Four 81 sq. ft. cartridges required; use Unicel C 7483(4) to replace full set. Can also be replaced with Unicel C 7477 or upgraded to Unicel C 7484. ...AND MORE