Fitment guide

How to identify your pool filter cartridge

Three ways to find the correct replacement cartridge: by the part number on the end cap, by the filter housing model, or by measuring the cartridge itself.

Ordering a replacement pool filter cartridge should be simple. In practice it is one of the more error-prone purchases a pool owner makes, because the same cartridge is sold under a different part number by nearly every brand that makes it. A cartridge might be a Unicel C-7470, a Pleatco PCC80, a Filbur FC-1976, or a Pentair 178580, and all four are the same physical part for the same filter. Someone who orders by matching a brand name instead of the actual fit can easily end up with the wrong thing.

This guide covers the three reliable ways to identify the cartridge you need, how to measure when the printing has worn off, and the specific mistakes that lead to wrong orders. The goal is to get you to the correct part on the first try.

Why part numbers are confusing

A single cartridge design gets manufactured and rebranded by many companies. Unicel, Pleatco, and Filbur are all aftermarket brands that produce equivalents of the same original equipment cartridge, and each assigns its own catalog number. The pool equipment maker, Pentair in this case, has its own set of numbers on top of that, sometimes more than one for the same part.

The result is that a cartridge with a single set of dimensions can carry six or more valid part numbers. None of them are wrong. They just come from different catalogs. When you search one number and a listing shows a different number, that is usually a correct cross-reference, not a mismatch. The way to be certain is to stop matching names and start matching the cartridge to your filter.

The three ways to identify your cartridge

Any one of these three methods will get you to the right part. Use whichever is available to you, and use a second one to double-check if you have any doubt.

1. By the part number on the end cap

The fastest method. Pull the cartridge out of the filter and look at the plastic end caps, top and bottom. The manufacturer usually prints the part number directly on the cap, molded or stamped into the plastic. You are looking for something like C-7470, PCC80, FC-1976, or a Pentair number such as 178580.

Once you have that number, you can match it directly, or match any of its cross-referenced equivalents. A cartridge printed PCC80 is replaced just as correctly by a C-7470, because they are the same part. If the number on your cap appears in the cross-reference table at the bottom of this page, any other number in that same group will fit.

The limitation of this method is wear. Cartridges spend their lives in moving water, and the printing on the end cap fades. If yours is unreadable, move to one of the next two methods.

2. By the filter housing model

If you cannot read the cartridge, identify the filter housing instead. The housing is the large tank the cartridge sits inside. It carries a label or a molded model name, usually near the top or on the collar, listing the system model. For the cartridge this guide focuses on, the housing reads Clean & Clear Plus 320, often shortened to CCP320.

The housing model tells you two things: which cartridge fits, and how many the system takes. The Clean & Clear Plus 320 uses four cartridges of the C-7470 type. Other Clean & Clear Plus sizes exist, such as the 240, 420, and 520, and they take the same style of cartridge in different lengths and counts, so read the number on the housing carefully. A 320 is not a 420.

This method is reliable because the housing model is a fixed fact about your equipment. It does not wear off the way a cartridge cap does, and it removes the guesswork of matching brand names.

3. By measuring the cartridge

When the cartridge is unlabeled and you cannot get to the housing model, measure. A cartridge is defined by a small number of dimensions, and matching them settles the identification without any part number at all.

Measure these four:

Dimension	What to measure	C-7470 value
Length	End cap to end cap, overall	20 1/16 in
Outer diameter	Across the outside of the pleats	7 in
Top opening	The hole in the center of the top cap	3 in
Bottom opening	The hole in the center of the bottom cap	3 in

If your cartridge measures 20 1/16 inches long, 7 inches across, with 3 inch openings at both ends, it is the C-7470 type and any cartridge in that cross-reference group replaces it. Measure to the nearest sixteenth of an inch. Small differences matter, because neighboring cartridge sizes are only an inch or two apart in length or diameter.

How to measure correctly

Lay the cartridge flat on a level surface. For length, measure the full distance from the outer face of one end cap to the outer face of the other, not just the pleated section. The end caps count.

For outer diameter, measure across the widest point of the pleats through the center of the cartridge. A cloth tape around the circumference divided by pi also works if you do not have a caliper or a long ruler, but measuring straight across is simpler.

For the openings, measure the diameter of the round hole in the center of each end cap. Some cartridges have the same opening at both ends, some do not, so check both. The opening is how the cartridge seats onto the filter's manifold, so it has to match even when the length and diameter already do.

Common mistakes

These are the errors that lead to a wrong cartridge showing up at the door.

Confusing outer diameter with opening diameter. This is the single most common mistake. The outer diameter is the full width of the cartridge across the pleats, 7 inches for the C-7470. The opening is the small hole in the end cap, 3 inches. Both are round, both are diameters, and it is easy to record one when you meant the other. A cartridge with the right length but the wrong opening will not seat properly.

Buying the wrong pack size. The Clean & Clear Plus 320 takes four cartridges. Numbers like PCC80-PAK4 or C-7470-4 mean a set of four of the same cartridge, not a different part. Ordering a single when you needed four, or assuming a four-pack is a larger cartridge, are both common. Match the part first, then choose the quantity your system needs.

Matching on appearance instead of specs. Many cartridges look nearly identical. Similar pleat count, similar color caps, similar overall shape. Appearance is not a reliable match. Two cartridges that look the same can differ by an inch in length or by the opening size, which is enough to not fit. Match by number or by measurement, not by eye.

Assuming a brand mismatch is an error. Seeing a C-7470 listed as a replacement for your PCC80 is not a mistake in the listing. They are equivalents. Rejecting a correct cross-reference because the brand name differs sends people hunting for an exact-brand match that costs more and fits identically.

When the cartridge needs replacing, not just cleaning

Identifying the right part is worth doing before you actually need it, because the point at which you order is usually the point at which the old cartridge is already failing. A cartridge that only needs cleaning is not the same as one that needs replacing, and knowing the difference tells you whether you are buying now or later.

Cleaning restores a cartridge that is dirty but intact. Rising pressure on the filter gauge, shorter runs between cleanings, or water that clears more slowly are signs of a cartridge loaded with debris, and a rinse or a soak brings it back. This is normal maintenance across a season.

Replacement is for a cartridge that no longer responds to cleaning. The pleated media breaks down over time. When the pleats flatten or spread, when the fabric thins or tears, or when a cleaning no longer drops the filter pressure back to where it started, the cartridge has reached the end of its service life. Cracked or brittle end caps are a replacement signal on their own, because a cap that no longer seals lets unfiltered water bypass the cartridge entirely. Most cartridges of this type last somewhere in the range of a few seasons depending on use, water chemistry, and how often they are cleaned, but the condition of the media is the real test, not the calendar.

Because the Clean & Clear Plus 320 runs four cartridges as a set, they tend to reach the end together, and replacing all four at once keeps the load even across the new set. This is the moment most owners go looking for a part number, which is exactly when the identification methods above matter most.

Cross-reference table

These part numbers all refer to the same cartridge for the Pentair Clean & Clear Plus 320. If your cartridge carries any one of them, any other in the list is an equivalent replacement.

Brand	Part number
Unicel	C-7470
Pleatco	PCC80
Filbur	FC-1976
Pentair OEM (set of 4)	179134
Pentair OEM (single)	R173573
Pentair / Pac Fab (single)	178580
Pentair OEM	817-0081
Aladdin	18005
Excel Filters	XLS-720
Baleen	AK-60433
Darlly	70804
Unicel (4-pack)	C-7470-4
Pleatco (4-pack)	PCC80-PAK4
Filbur (4-pack)	FC-6465

For the detail on any single number, see the individual part pages: