Unicel C-8475 | 75 sq ft Coleman & Maax Spa Filter

The Unicel C-8475 is a 75 square foot replacement spa filter cartridge for Coleman Spas and Maax Spas of Arizona, replacing OEM part numbers 100594 and 3301-2262. At 8" in diameter and 13" tall with 197 pleats, it is a large, high-capacity cartridge built for spas that carry real bather load.

What sets it apart mechanically is the bottom connection: a 2" male slip fitting. Not a thread, not an open end — a smooth, unthreaded collar that seals by close tolerance against a matching socket in the filter well, the same principle as a PVC slip joint. There is nothing to screw on and nothing to align. You push it straight down and the fit itself makes the seal.

That design has a real advantage and one thing you have to respect. The advantage is that a slip fitting cannot be cross-threaded, which is the single most common way people damage a threaded cartridge. There are no threads to strip, so installation is faster and the connection is more forgiving of repeated removal — which matters on a cartridge you will pull for cleaning a dozen times a year. The thing to respect is that a slip fitting gives you no positive confirmation that it is fully home. A threaded cartridge stops turning when it is seated. A slip fitting will sit half-inserted, feel reasonably solid, and hold its position — while leaving a gap that lets unfiltered water slip past the media straight into your suction line. Seating it fully is the whole job, and it takes about three extra seconds.

The media is Unicel's standard 3 oz Reemay polyester — one hundred percent polyester over a solid injection-molded core, with chemical-resistant end caps molded to an exact OEM fit, capturing suspended particles down to roughly 20 microns. Made in the USA by Meissner Manufacturing, with more than 45 years behind the Unicel name, and specified to meet or exceed the factory cartridge it replaces.