OEM vs Unicel vs Pleatco spa filters: what’s the difference?
By MySpaFilter Editorial Team · Last reviewed
Spa makers (OEMs such as Hot Spring, Jacuzzi or Sundance) assign their own part numbers; Unicel and Pleatco are aftermarket cartridge makers that publish cross-reference tables mapping those OEM numbers to their own replacements[5][2]. A cross-referenced replacement is listed as matching the original’s dimensions and fittings.
How the numbers relate
| Who makes it | Example numbering | |
|---|---|---|
| OEM | Sold by or for the spa maker | Brand-specific (e.g. Caldera 74148) |
| Unicel | Unicel (aftermarket) | C-xxxx (e.g. C-4335) |
| Pleatco | Pleatco (aftermarket) | Pxxx / PRBxx (e.g. PRB35-IN) |
Example from our data: Caldera OEM 74148 ↔ Unicel C-4335 ↔ Pleatco PRB35-IN, cross-referenced in the Unicel 2026 guide and Pleatco 2023 catalog[5][2].
What spa makers recommend
Spa makers generally recommend their own filters: Hot Spring says to replace with genuine Watkins filters[7], and Jacuzzi recommends filters designed for your specific spa model[10]. Check your spa’s warranty terms before switching.
Things to verify before buying
- Diameter, length and both end fittings match.
- Special designs (e.g. Hot Spring TRI-X, or Sundance two-stage assemblies with disposable inserts[12]) may not have a direct aftermarket equivalent.
- We flag rows we could not confirm in two sources as unverified.
Browse by brand: Caldera, Hot Spring, Hot Spot, Jacuzzi, Sundance.
FAQ
Are Unicel and Pleatco filters the same as OEM?
They are aftermarket cartridges that their makers cross-reference to OEM part numbers based on matching size and fittings. They are not made by the spa manufacturer.
Will an aftermarket filter void my warranty?
We can’t say for your spa; check your warranty. Hot Spring, for example, recommends genuine Watkins replacement filters.
Is a Unicel C-number the same as a Pleatco number?
Pleatco’s catalog cross-references Unicel numbers to its own, so a matched pair should fit the same housing.
Sources
- Pleatco 2023 Catalog (Pentair)
- Unicel — Maintenance & FAQ
- Unicel 2026 Replacement Guide
- Hot Spring Spas — Maintenance Tips
- Jacuzzi — Hot Tub Filter Cleaning Made Easy
- Sundance Spas 780 Series Owner’s Manual (2024)
This guide summarizes published manufacturer guidance; always follow your own spa’s owner’s manual. See our disclaimer.