Pentair 36" FNS Plus Grid Replacement Pack

The Pentair 36" FNS Plus Grid Replacement Pack (Part #59023500) is a comprehensive core-filtration replacement kit engineered exclusively for the Pentair FNS® Plus 36 Square Foot Vertical Grid Diatomaceous Earth (D.E.) Pool and Spa Filter.

The kit contains a complete matrix of eight pre-sewn filtration elements: seven full-sized curved grids and one partial (narrower) grid. Each individual grid is constructed from high-tensile, chemical-resistant polypropylene cloth tightly stretched over an internal, injection-molded structural raw polymer frame. The narrow partial grid is strategically integrated to provide a dedicated installation gap for the filter vessel's internal top air bleed extension tube.

When arranged in a circular formation and clamped tightly between the filter's top manifold and bottom locator plate, these grids create a 36-square-foot surface area. Once coated evenly with raw D.E. powder, this grid nest mechanically intercepts organic debris, fine silt, and algae spore matrices down to an industry-leading 3 to 5 microns. Replacing the entire bundle at once cures uneven pressure drops caused by isolated fabric tears, worn stitching, or mineral-calcified fabric pores that regular backwashing can no longer clear.

Weight and Dimensions Profile

Because this kit bundles all eight individual structural fabric grids together into a single box, it carries a broad and rigid shipping footprint:

• Grid Height: Individual grid elements measure exactly 18 inches long (the industry-standard measurement designating a 36-square-foot Pentair tank capacity core).

• Actual Product Weight: Approximately 13.5 to 14.5 pounds for the combined bare weight of all eight nested elements.

• Packaged Shipping Weight: Typically scales at 18.0 to 20.0 pounds due to the wide, heavy-duty cardboard box and internal stabilization dividers necessary to shield the rigid plastic grid frames and delicate outer mesh from being crushed, snapped, or torn during transit.