Pentair Lower Tank Assembly

The Pentair Lower Tank Assembly (commonly designated by OEM parts such as #178578 for Clean & Clear Plus/Quad D.E. systems, #178560 for smaller Clean & Clear units, or #178743Z for Posi-Clear PXC models) is a high-strength pressure vessel base that anchors commercial and residential pool filtration systems. Typically injection-molded from specialized fiberglass-reinforced polypropylene, this almond or black polymer basin is engineered to safely absorb continuous hydraulic pressure spikes, chemical exposure, and outdoor weathering. It incorporates molded bulkhead connection openings to host the internal plumbing manifolds and link up with external inlet/outlet union pipes. Acting as the physical core that holds filter cartridges, sand beds, or D.E. grids, this structural lower half permits targeted repairs for cracked basements without requiring the complete purchase of a brand-new entire filtration system.

Depending on the specific filter footprint and volume capacity, the actual product weight varies across the product line:

• Pentair 178743Z (Posi-Clear PXC Small Base): Features an actual product weight of approximately 12.0 pounds.

• Pentair 178560 / 178578 (Clean & Clear / Plus Series Base): Weighs between 12.0 and 20.6 pounds on its own, with a full boxed transit shipping weight reaching up to 28.0 pounds for the heaviest variations.

Pentair Filter Tank Bottom Replacement Tutorial provides a step-by-step visual demonstration on how to safely replace a damaged or leaking lower tank assembly on a Pentair cartridge filter system.