Description
Overview
The Unicel 4CH-940 is a pleated polyester spa cartridge filter element providing 40.0 sq ft of filtration area in a compact, high-capacity form factor engineered for premium spa circulation systems. Dimensional specifications: 4.625-inch OD, 2.125-inch ID, 9.25-inch overall length with a closed-bottom, open-top end cap configuration. Construction features Reemay nonwoven polyester media with nominal 15-micron filtration efficiency, ABS injection-molded end caps with UV-stabilized adhesive bond, and a perforated polypropylene core for axial rigidity under spa pump differential loading. Maximum rated continuous service temperature: 115°F, with intermittent excursions to 120°F acceptable per manufacturer test protocol. End cap geometry holds ±0.020-inch OD tolerance for confirmed bypass-free seating in OEM housings.
Spa cartridge service intervals run accelerated relative to pool applications due to higher bather-load-to-water-volume ratios and elevated operating temperatures. Recommended service cycle: fresh-water rinse every 2–4 weeks; chemical soak with dilute TSP or commercial enzyme cleaner every 4–6 weeks to remove body oils, lotions, and surfactant residue that resist standard rinsing. Replace element at ≤ 12-month intervals under typical residential spa duty, or sooner when ΔP rises ≥ 5 PSI above clean-filter operating baseline. Chemical compatibility: polyester media tolerates continuous service at ≤ 10 ppm free available chlorine or ≤ 30 ppm total bromine; muriatic acid wash at 1:20 dilution compatible for calcium scale removal (20-minute maximum exposure, thorough rinse before reinstallation); enzyme cleaners compatible without restriction. ABS end cap adhesive is acid-wash compatible. Standard Unicel 90-day manufacturing defect warranty applies through authorized distribution.
What’s Included
Your order includes the selected quantity of replacement spa filter cartridges. Each unit is individually inspected for quality before shipping.
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