{"product_id":"unicelreplacementfiltercartridge50sfcalspamartecc4305unfc4305","title":"Unicel Replacement Filter Cartridge 50 sf Cal Spa\/Martec | C-4305","description":"\u003cdiv class=\"product-description\"\u003e\n  \u003ch2\u003eUnicel C-4305 Replacement Spa Filter Cartridge – 50 Sq Ft (Open Top \u0026amp; Bottom, 2-1\/8\" ID)\u003c\/h2\u003e\n\n  \u003cp\u003e\n    The Unicel C-4305 is a premium \u003cstrong\u003e50 sq ft\u003c\/strong\u003e pleated replacement filter cartridge used in many hot tub and spa\n    filtration systems that take a \u003cstrong\u003e4-15\/16\" diameter\u003c\/strong\u003e cartridge with \u003cstrong\u003eopen ends\u003c\/strong\u003e. Replacing a worn or torn\n    cartridge helps restore circulation, improve water clarity, and reduce strain on the spa pump and heater.\n  \u003c\/p\u003e\n\n  \u003ch3\u003eKey Features\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003e50 sq ft\u003c\/strong\u003e filtration area for strong debris capture and steady flow\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOpen top \u0026amp; open bottom\u003c\/strong\u003e design for standpipe-style housings\u003c\/li\u003e\n    \u003cli\u003eDurable pleated media and rigid inner core built for repeated cleanings\u003c\/li\u003e\n    \u003cli\u003eCommon replacement when pleats are torn, flattened, or won’t clean up well\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eSpecifications\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e C-4305\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFiltration Area:\u003c\/strong\u003e 50 sq ft\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOutside Diameter:\u003c\/strong\u003e 4-15\/16\" (4.9375\")\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eLength:\u003c\/strong\u003e 14-7\/8\" (14.875\")\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTop End Cap:\u003c\/strong\u003e Open\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eTop Inside Diameter:\u003c\/strong\u003e 2-1\/8\" (2.125\")\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eBottom End Cap:\u003c\/strong\u003e Open\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eBottom Inside Diameter:\u003c\/strong\u003e 2-1\/8\" (2.125\")\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003ePleat Count (typical):\u003c\/strong\u003e 193\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eMedia:\u003c\/strong\u003e 3 oz pleated media\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eReplaces \/ Cross References\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFilbur:\u003c\/strong\u003e FC-1630\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003ePleatco:\u003c\/strong\u003e PMT45 (often also listed as PMT50 depending on application catalog)\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eDarlly:\u003c\/strong\u003e 40454\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eSundance:\u003c\/strong\u003e 6540-497 (common reference)\u003c\/li\u003e\n    \u003cli\u003e\n\u003cstrong\u003eOther references:\u003c\/strong\u003e 15003\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eCompatibility Notes\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eMany spas use similar-looking cartridges—confirm by matching the \u003cstrong\u003eOD\u003c\/strong\u003e, \u003cstrong\u003elength\u003c\/strong\u003e, and \u003cstrong\u003e2-1\/8\" open ends\u003c\/strong\u003e.\u003c\/li\u003e\n    \u003cli\u003eIf your current filter has a handle, threads, or a different inside opening, you likely need a different cartridge.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eWhen to Replace\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003ePleats are torn, frayed, or separating from end caps\u003c\/li\u003e\n    \u003cli\u003eFilter stays restrictive even after a deep clean and thorough rinse\u003c\/li\u003e\n    \u003cli\u003eWater stays cloudy despite proper sanitizer and balanced chemistry\u003c\/li\u003e\n    \u003cli\u003eEnd caps are cracked\/warped or the inner core is collapsing\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eRelated Products\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=Unicel%20C-4305\"\u003eUnicel C-4305 (Shop \/ Options)\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=spa%20cartridge%20filter%20cleaner\"\u003eSpa Cartridge Filter Cleaner\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=cartridge%20cleaning%20wand\"\u003eCartridge Cleaning Wand\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=spa%20water%20test%20strips\"\u003eSpa Water Test Strips\u003c\/a\u003e\u003c\/li\u003e\n    \u003cli\u003e\u003ca href=\"https:\/\/aquapoolsupply.com\/search?q=spa%20scale%20remover\"\u003eSpa Scale Remover\u003c\/a\u003e\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003ch3\u003eMaintenance Tips\u003c\/h3\u003e\n  \u003cul\u003e\n    \u003cli\u003eRinse the cartridge regularly (often weekly with heavy spa use) to prevent restriction and keep jets performing well.\u003c\/li\u003e\n    \u003cli\u003eDeep clean every 3–6 weeks with a cartridge cleaner to remove oils; rinse thoroughly before reinstalling.\u003c\/li\u003e\n    \u003cli\u003eIf scale is present, degrease first, then treat for scale, and rinse completely before returning the filter to service.\u003c\/li\u003e\n    \u003cli\u003eRotating between two cartridges (one in use, one drying after cleaning) can extend overall filter life and improve performance.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n","brand":"Unicel","offers":[{"title":"Default Title","offer_id":46797840515247,"sku":"C-4305","price":42.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0734\/6415\/2239\/files\/unicel-replacement-filter-cartridge-50-sf-cal-spamartec-c-4305-cartridges-3242997.jpg?v=1777068028","url":"https:\/\/freshized.com\/products\/unicelreplacementfiltercartridge50sfcalspamartecc4305unfc4305","provider":"Freshized","version":"1.0","type":"link"}