Caldera 73531 | 75 sq ft Utopia Spa Filter

The Caldera 73531 filter cartridge is a factory-original replacement covering a wide range of Caldera spas. With 75 square feet of filtration across 260 pleats of heavy-duty polyester, it delivers more efficient filtration and better water clarity — so you spend less time cleaning and more time enjoying your hot tub.

Filtration is the quiet backbone of good 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 cartridge is the workhorse of the Caldera lineup — it serves more models across more series than any other size, from Paradise® Series spas like Salina and Makena to Highland, Aquatic Melodies, and C-Series models. Caldera specifies a heavy-duty polyester media designed to outlast cheaper alternatives, and a semi-circular handle on top makes lifting the cartridge out for cleaning effortless. Like all Caldera filters, it's made in the USA.