{"product_id":"unicel-filter-cartridge-19-sf-4ch-21","title":"Unicel 4000 Series 19 sq. ft. Replacement Filter Cartridge | 4CH-21","description":"\u003cp\u003eThe Unicel 4CH-21 is a \u003cstrong\u003e4000 Series 19 sq. ft. replacement filter cartridge\u003c\/strong\u003e engineered for top-load spa and hot tub filtration systems with a 1-1\/2\" MPT threaded suction connection. With \u003cstrong\u003e158 pleats of 3 oz. Reemay 2033 polyester media\u003c\/strong\u003e, this cartridge delivers consistent particle capture and reliable water clarity in compact spa filter housings. The molded cone handle on top simplifies removal at service time, while the 1-1\/2\" male pipe thread bottom threads directly into the spa's suction fitting — no separate adapter required on most compatible systems.\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; margin: 20px 0; border: 1px solid #ccc;\"\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eFilter Area\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e19 sq. ft.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eLength\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e8\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eOuter Diameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e4 5\/8\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eTop Inner Diameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eN\/A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eBottom Inner Diameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eN\/A\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e3 oz. Reemay 2033\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003ePleat Count\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e158\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 15px 15px 0 15px; text-align: center;\"\u003e\n\u003cdiv style=\"font-size: 12px; margin-bottom: 8px;\"\u003e\n\u003cstrong\u003eTop Cap:\u003c\/strong\u003e molded cone handle\u003c\/div\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0920\/0687\/5411\/files\/molded_cone_handle1.gif\" alt=\"Top Cap\" style=\"max-width: 100%; height: auto; margin: 0; padding: 0;\"\u003e\n\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 15px 15px 0 15px; text-align: center;\"\u003e\n\u003cdiv style=\"font-size: 12px; margin-bottom: 8px;\"\u003e\n\u003cstrong\u003eBottom Cap:\u003c\/strong\u003e 1-1\/2\" male thread\/MPT\u003c\/div\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0920\/0687\/5411\/files\/male_thread123.gif\" alt=\"Bottom Cap\" style=\"max-width: 100%; height: auto; margin: 0; padding: 0;\"\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eFits into:\u003c\/h3\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; margin: 20px 0; border: 1px solid #ccc;\"\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eOEM Brand\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eProduct Name\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003ePart Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e\u003cstrong\u003eNotes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eAlcove\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003e-\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eAtera Spas (Four Seasons Home Resort Products)\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003e-\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eDream Maker Spas\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003eRemove pad adaptor (if present) from skimmer before threading MPT directly into suction fitting; 2000 to present w\/LED lights\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePageant Spas\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003e-\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eSaratoga Spas\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e20245-238\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003e-\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background-color: #f8f9fa;\"\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eUnicel\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e19 sq. ft. top load\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003eDesigned for systems using a 1-1\/2\" MPT threaded connection. Also replaces open-bottom filters (approx. 1.9\" inner diameter) previously used with a separate removable threaded adapter in the spa's suction fitting.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003eVita Spas\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003e-\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px;\"\u003ePVT 25N\u003c\/td\u003e\n\u003ctd style=\"border: 1px solid #ccc; padding: 10px; font-size: 0.9em;\"\u003eRemove pad adapter from the skimmer before threading Unicel MPT directly into the suction fitting.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\u003cem\u003e(This is not an exhaustive list.)\u003c\/em\u003e","brand":"Unicel","offers":[{"title":"Default Title","offer_id":52133503664403,"sku":"4CH-21","price":36.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0920\/0687\/5411\/files\/4CH-21__4CH-21_1.jpg?v=1771455698","url":"https:\/\/poolaroo.com\/products\/unicel-filter-cartridge-19-sf-4ch-21","provider":"Poolaroo","version":"1.0","type":"link"}