Pentair Bracket Anchor Kit

The Pentair Titan / FNS Plus Lower Grid Retainer (part number 59000500, also referred to as the spider grid locator or grid holding wheel) is a critical internal indexing component engineered exclusively for the vertical grid nest assembly of high-capacity Diatomaceous Earth (D.E.) pool and spa filtration systems. This genuine original equipment manufacturer (OEM) part serves as the foundational alignment ring for the entire product line of Pentair FNS Plus filters (models FNSP24, FNSP36, FNSP48, and FNSP60), while offering cross-compatibility with legacy American Products Titan D.E. filter series.

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Injection-molded from a heavy-walled, high-impact, and chemically inert polymer composite material, the retainer is styled as a flat, multi-spoke template grid with a diameter of approximately 17.5 inches. Its primary operational role is to establish rigid, precise bottom alignment for the internal filtration core. The perimeter of this spider wheel features specialized indexing slots designed to grip and seat the lower feet of seven full-sized curved D.E. fabric grids and one partial grid. The central section of the plate includes two dedicated structural openings that receive the dual stainless steel vertical tie rods extending downward from the top manifold. When these rods are tensioned, the lower grid retainer acts as a stabilization base that prevents the 12-to-30-inch-tall grid elements from shifting, tilting, or collapsing under heavy hydraulic circulation pressures. By holding the filter grids in a uniform radial pattern, it maintains a perfect hydraulic balance across the media bed and ensures no raw water or loose D.E. powder can bypass the filter core.

Built to remain permanently submerged at the base of a pressurized vessel under continuous parameters up to 50 PSI, its advanced engineering matrix completely resists structural warping, stress-cracking, and advanced corrosion from prolonged exposure to intense sunlight, shifting seasonal temperatures, and highly concentrated sanitizers like chlorine, bromine, or muriatic acid scale washes. Due to its wide, lightweight open-spoke configuration, this replacement lower grid retainer carries a net product and shipping weight of approximately 2.10 pounds (about 33.6 ounces).