Unicel C-8399 | 100 sq ft Caldera Spa Filter

The Unicel C-8399 is a large-capacity spa filter cartridge delivering 100 square feet of filtration across 259 pleats of Reemay® 2033 polyester media, capturing debris down to an average of 20 microns. Built to meet or exceed OEM specifications, it's the replacement cartridge for Caldera® Spas, taking the place of Caldera part 1039607. Filtration is the quiet backbone of clean spa water. Every soak leaves behind body oils, lotions, hair, and fine debris, and the cartridge is what removes all of it before it clouds the water, feeds bacteria, or coats your plumbing. When a filter is worn or clogged, the effects spread everywhere: dull water, higher chemical use, softer jets, and a pump and heater straining against restricted flow. This is a serious cartridge — 16-1/2 inches tall with a full 100 square feet of filtering surface packed into 259 pleats, one of the highest pleat counts Unicel makes. That capacity is exactly what a large, jet-heavy Caldera spa demands. A semi-circular handle molded into the top makes lifting it out effortless, while the 3-5/8 inch open bottom with a lip seal seats into the housing for a positive, leak-free connection. Add Reemay's trilobal fibers and chemical-resistant end caps, and you get a cartridge built to perform through cleaning after cleaning. Made in the USA. Pro Tip: Pay attention to the lip seal on the bottom end cap. That molded seal is what forces water to travel through the pleats rather than slipping around the edge of the cartridge — and it's easy to compromise. Make sure the bottom seats squarely and completely in the housing when you install it, and check the seal for nicks or distortion whenever you clean the filter. A cartridge that isn't sealing properly filters far less than its rating suggests. Brand UNICEL®