Pool Filter Cross-Reference: How Unicel, Pleatco, and Filbur Numbers Map to Each Other

Three lookup paths, in order of power: ① your cartridge’s part number — Unicel C-xxxx, Pleatco PA/PAP/PAE/PXST…, Filbur FC-xxxx, or OEM numbers like Hayward CX-xxxxRE and Pentair R17xxxx cross-map directly; ② your filter’s brand and model — Pentair Clean & Clear 200, Hayward Star-Clear C900, and so on; ③ the tape-measure fallback. An interactive cross-reference tool runs all three in one step: the cross-reference lookup.

The pool-filter market runs on a three-brand replacement ecosystem — Unicel (owned by Pentair), Pleatco, and Filbur — that manufactures equivalents for every major OEM cartridge, plus OEM’s own parts. Cross-referencing is the skill that lets you buy any of the four for the same slot. Search for it (a modest headline volume, but a deep long tail of part-number queries) and the results are almost entirely product pages and finder widgets — the teaching of how the numbering works is essentially unclaimed. This page claims it.

Quick Answer: Real Cross-Reference Rows

Each row is one physical cartridge sold under four numbers — the lookup table’s raw material:

The C-9419 row is the canonical example: 200 sq ft, 10-1/16″ outside diameter × 31-1/8″ long, open/open caps — buy any of its four numbers and you’re buying the same cartridge specification. The C-8409 row (90 sq ft, 8-15/16″ × 17-3/8″, 174 pleats) is the Star-Clear classic.

The Numbering Systems, Decoded

Unicel C-xxxx. The de facto common language of cartridge cross-referencing — even competitors’ compatibility charts are organized around Unicel numbers. “C” is the cartridge series; the four digits are the cartridge pattern (not a size code — the pattern encodes dimensions and sq ft and cap configuration together). Owned by Pentair since its acquisition of the brand, which is why Unicel coverage of Pentair-family OEM numbers is the widest in the ecosystem.

Pleatco PA / PAP / PAE / PXST / PCC… Pleatco prefixes carry meaning: PA is the standard cartridge line (PA90 = Star-Clear 90’s equivalent), PAP the Pentair Clean & Clear-focused family (PAP200 = CC200), PAE/PRB/PXST lines cover specific OEM platforms (Dynamic Series, XStream), PCC the Clean & Clear Plus pattern, PFAB/PJW/PCH cover spa jets and specialty configs. If your cartridge’s number starts with a two-to-four-letter Pleatco prefix, it’s the manufacturer’s own system — cross-map it to Unicel/Filbur via any lookup.

Filbur FC-xxxx. Filbur’s four-digit numbering is its own sequence (FC-0688 = the C-9419 equivalent — no digit correspondence between brands; don’t try to derive one). Filbur manufactures in the US and consistently prices below the other two, which is why price-shopping a cross-reference row usually lands on the FC- number.

OEM numbers. Hayward’s CX-xxxxRE (CX900RE = Star-Clear C900’s factory cartridge) and CCX-xxxxRE for XStream; Pentair’s R17xxxx (R173217 = the CC200 cartridge). The OEM number is what’s printed on the tank’s label and in its manual — often the easiest number to find, since cartridge caps fade but manuals and tank labels survive.

The meta-skill: find any one number, get all four. That’s what a cross-reference tool automates — and what the compatibility charts in product listings show in their “replaces” clauses.

The Three Lookup Paths (Worked)

Path 1 — cartridge number → matches. Cap prints “C-9419” → lookup returns PAP200, FC-0688, R173217, plus every compatible listing (“compatible with / replaces” language). Thirty seconds, zero ambiguity.

Path 2 — tank model → cartridge. Tank label reads “Hayward Star-Clear C900” → the model maps to its factory cartridge (CX900RE) → cross-reference expands to C-8409 / PA90 / FC-1292. Use this when the old cartridge is gone or illegible.

Path 3 — measurements → candidates → disambiguate by sq ft. OD × height × openings produces a shortlist; the square-footage rating and tank model break the tie (same-size/different-area cartridges exist — the full traps are in how to measure a pool filter cartridge).

The “Compatible With” Clause (What Legitimate Listings Say)

Aftermarket cartridges legally reference the OEM numbers they replace using “compatible with,” “replaces,” or “fits” clauses — e.g., a listing titled “Replacement for Unicel C-9419 / Pleatco PAP200 / Filbur FC-0688 — Pentair Clean & Clear 200.” That clause structure is the aftermarket’s standard compliance language: it asserts fitment, not affiliation. What you should not see is branding that implies it’s the OEM part itself. This distinction — and the quality question of which equivalent to actually buy (pleat counts and sq ft can differ 10–20% within the same cross-reference row) — is the whole subject of Unicel vs Pleatco vs Filbur, and the honest retail version of it lives in our own compatible-cartridge listings: same cross-reference row, stated pleat/sqft specs, no pretense of being the factory part.

FAQ

Are Unicel, Pleatco, and Filbur cartridges interchangeable?

When they share a cross-reference row, yes — each row is one cartridge specification sold under multiple numbers (e.g., C-9419 / PAP200 / FC-0688 for the Pentair Clean & Clear 200). The failures come from wrong-number substitutions, not wrong brands: same dimensions but wrong square footage or cap config is what leaks and throttles.

How do I find my pool filter’s part number?

Check the cartridge end-caps first (molded or printed — Unicel prints the top cap), then the filter tank’s label and manual (OEM numbers like CX900RE or R173217 live there), then any prior receipts. Any single number expands to the full cross-reference row via a lookup tool.

What does a Unicel number like C-9419 mean?

“C” is Unicel’s cartridge series; the four digits identify a specific cartridge pattern — dimensions, square footage, and end-cap configuration together. The digits don’t encode size in a decodable way; they’re pattern IDs to be looked up, not calculated.

Is an aftermarket “replaces” cartridge as good as OEM?

The reputable three (Unicel, Pleatco, Filbur) all produce OEM-equivalent performance for matched numbers — Unicel is Pentair-owned. Quality spread within a cross-reference row shows up in pleat count and actual media area, which can differ 10–20% between brands at the same nominal spec; compare those two specs, not logos. Details: Unicel vs Pleatco vs Filbur.

Can I cross-reference with just measurements?

Yes, as the third-best path: OD × total height × top/bottom openings gives a shortlist, then the tank model and square-footage rating disambiguate. Measurement-only ordering risks the same-size/different-sqft trap, so always confirm against the tank’s rated area.

Is there a Pleatco filter size chart — or a Unicel replacement guide?

Not in the “dimensions per number” sense the phrase implies, and that’s by design: Pleatco and Unicel numbers encode cartridge patterns (dimensions + sq ft + cap configuration together), not decodable sizes — so the usable “size chart” is the cross-reference row itself, which is exactly what the table above and the cross-reference lookup give you. If you arrive holding a single number — a Unicel C-4326, a Pleatco PAP100, a Filbur FC-0359, whatever’s left on your faded cap — paste it into the lookup and the row returns every equivalent number plus the spec block; that one-number-in-all-four-out path is faster and more current than any static PDF chart, which is why the reputable manufacturers publish lookup tools rather than printable guides.

Sources & References

• Cross-reference dataset (pool cartridge library, 487 cartridges crawled & reconciled 2026-08-19) — every row in the table above, including specs (C-9419: 200 sq ft, 10-1/16″ × 31-1/8″; C-8409: 174 pleats). Cross-reference database data (explicit).
• Manufacturer catalogs (Unicel, Pleatco, Filbur, Hayward, Pentair) — number placements and prefix families. Official documentation (explicit).
• Aftermarket compliance conventions — “compatible with/replaces” clause standards. Industry convention (explicit).

Related Guides

• How to Measure a Pool Filter Cartridge — the fallback path.
• Unicel vs Pleatco vs Filbur — choosing within the row.
• How Often to Replace Pool Filter Cartridge — when you’ll need this page again.
• How to Clean a Pool Filter Cartridge — the other half of cartridge care.

Shop this guide: Pool & spa filter cartridges