Built to Fit: Compatible with Hot Spring Spas, Hot Spot Spas, Solana Spas, and any systems that needs 5 7/8 inch (outer diameter) by 10 1/2 inch (length) filters. PWK30 hot tub filter cartridge replaces Unicel C-6430, Filbur FC-3915, Pleatco PWK30, Watkins 31489, 73178, 73250, 71825 3X More Effective Filtration: NSF 50 certified and designed with ultrafine particle technology to capture 3× more debris than standard filters, effectively trapping leaves, hair, sand, oily residue, and sediment for crystal-clear water Built to Last: Our PWK30 spa filter replacement features corrosion-resistant end caps that withstand chemicals and harsh conditions without melting or degrading. Reinforced pleated fibers resist deformation, ensuring consistent, reliable performance Washable & Reusable: The advanced trilobal structure prevents large particles from entering, ensures even debris distribution and prevents clogs—promoting quicker and easier rinsing to reduce cleaning time Less Frequent Cleaning: The free-flow core allows for better water circulation and reduces clogging, extending the time between cleanings. What once required bi-weekly maintenance now only needs attention once a month Enjoy crystal-clear spa water with Fil-fresh PWK30 hot tub filter cartridge, designed to work with Hot Spring Spas, Hot Spot Spas, Sovereign, Solana Spas, and any systems that needs 5 7/8 inch (outer diameter) by 10 1/2 inch (length) filters. It replaces cartridge models including Unicel C-6430, Filbur FC-3915, Pleatco PWK30, Watkins 31489, 73178, 73250, 71825, Baleen AK-5005, Darlly 60301, Harmsco H-6430, and Magnum HS30. Made from premium trilobal polyester, this high-efficiency spa filter captures hair, leaves, dust, and sediment with ease. A quick rinse once a month keeps it working like new, so your spa stays fresh, clean, and always ready for relaxation with less maintenance.