Pentair Posi-Clear™ RP PXCRP150 150 SqFt Cartridge Filter 56 - 150 gpm. The Posi-Clear RP Cartridge Pool Filter features a fiberglass-reinforced, chemical-resistant, polypropylene tank with no-tool servicing for easier cleaning. It also features a side-entry port, which provides nearly 50% more efficiency than any other single-cartridge pool filter available. Inside, it has increased cartridge surface consistency to block and trap particles as small as 20 microns. The result is picture-perfect pool water and lower energy use.