Unicel C-4320 Cartridge, 20 Sq. Ft.

The Unicel C-4320 is a replacement pool filter cartridge rated at 20 square feet. It measures 4-5/8 inches across the outside diameter and 11-7/8 inches long.

Match it by the numbers

Cartridges are identified by diameter, length, area and end configuration, and several of them look nearly identical on a shelf. Pull the old element, measure it, and match the Unicel part number. That is faster and more reliable than trying to work back from the filter housing model, particularly on equipment that has been swapped around over the years.

Cleaning against replacing

A cartridge is cleaned when filter pressure climbs above its clean starting point, and replaced when cleaning stops working. Pleats that stay grey after a proper soak and rinse, media that feels soft, or splits at the folds all mean the element is finished, no matter how it looks from a distance.

Check the quantity

This is one cartridge. Some housings hold a single element and others hold several, so count what you take out.