Pentair 136 SqFt Small Inner Replacement Cartridge

The Pentair 136 SqFt Small Inner Replacement Cartridge (part number 178583) is a precision-engineered internal filtration element designed exclusively for use within Pentair Clean & Clear Plus 520 cartridge pool and spa filtration systems, where it nests together with three larger outer cartridges to provide a combined 520 square feet of heavy-duty filtering area. Fabricated from a premium, high-density spunbound polyester fabric, this core cartridge features uniform, sharp-creased pleats that effectively capture and trap micro-particles, dirt, and fine debris down to the single-digit micron level. The pleated fabric media is structurally supported by a rugged, impact-resistant ABS plastic center core that prevents collapse under intense hydraulic pressure, while high-durability polyurethane end caps ensure an airtight and watertight bypass seal within the filter tank. Built to withstand continuous exposure to concentrated pool sanitizers like chlorine, acid washing, and fluctuating water temperatures, this internal core cartridge optimizes water clarity and flow efficiency. Engineered with a specialized, slimmer profile to fit perfectly inside the multi-cartridge manifold grid, this single inner element carries an individual product and shipping weight of approximately 2.40 pounds.