The Unicel 5CH-752 is a 75 square foot top-load replacement cartridge for Cal Spas, and it is a genuinely impressive piece of packaging. Seventy-five square feet of filtration is normally the territory of wide-body cartridges eight inches or more across. This one delivers it from a slender 5-3/16″ diameter, achieved by running tall — 16-1/8″ — and folding the media into 194 pleats. The result fits into a narrow filter well that a wide cartridge could never enter, without giving up the capacity a full-size spa demands.
Capacity is worth caring about for a reason that gets misunderstood. It does not make a filter clean better on any given pass. It determines how long the filter keeps performing before accumulated debris starts choking flow. Spread the same load across 75 square feet instead of 40 and the cartridge clogs more slowly, holds jet pressure steadier between cleanings, and asks less of a circulation pump that would otherwise be straining to pull water through progressively tighter media. On a spa carrying real bather load, that is the difference between rinsing monthly and fighting with the filter every other week.
The connection is a 2″ male pipe thread molded into the bottom end cap, with a bar handle across the closed top. The cartridge screws directly onto the suction fitting in the floor of the filter well, which means it is the connection — water cannot reach the pump without passing through the media, because the only path into the suction line runs through the inside of the cartridge. The bar handle gives you a proper two-finger grip to twist against, which matters on a cartridge this tall that has been sitting submerged in 100-degree water.
Media is 3 oz Reemay 2033 — one hundred percent spunbonded polyester over a solid injection-molded core, with chemical-resistant end caps molded to an exact OEM fit. Made in the USA by Meissner Manufacturing, with more than 45 years behind the Unicel name.
Pro Tip: The bar handle is the most useful and the most dangerous feature on this cartridge. It gives you real mechanical advantage over a 2″ thread — and that leverage is exactly the problem. A molded plastic thread that you could never overtighten by gripping the body directly is easy to crank well past snug with a bar handle in your fist. Turn until you feel resistance, then stop. Overtightening either cracks the end cap outright or seizes the cartridge so thoroughly that the next person to change it has to destroy it to get it out. Use the handle for grip, not for torque.
Brand
UNICEL®
