Abstract: A replacement filter cartridge assembly for hot tubs, spas and other aquatic environments includes a top end cap, a bottom end cap, a perforated elongated core extending between the end caps, and a pleated filter medium situated between the end caps and disposed circumferentially about the core. The replacement filter cartridge assembly is removably rotatably attachable to an adaptor of a filtering apparatus having a pair of diametrically opposed prongs extending outwardly therefrom. The bottom end cap has a central opening and a pair of diametrically opposed notches situated at the periphery of the central opening. The replacement filter cartridge assembly includes an internal lock ring which is situated on the core at the bottom end cap. The internal lock ring has one or more surfaces which engage the prongs of the adaptor to removably secure the replacement filter cartridge assembly to the adaptor of the filtering apparatus.

Abstract: A replacement filter cartridge assembly includes a filter cartridge element and a reusable supporting core assembly. The filter cartridge element is cylindrical in shape and has top and bottom end caps. Either the top end cap or the bottom end cap has an opening formed through its thickness which communicates with a central bore extending longitudinally through the filter cartridge element. The supporting core assembly includes a perforated tubular core and a sealing end cap mounted on one end of the core. The core is inserted through the top or bottom end cap opening and into the central bore of the filter cartridge element. The sealing end cap rests against either the top or bottom end cap of the filter cartridge element, while the other end of the tubular core contacts the inner side of the opposite end cap of the cartridge element.