Hot Tub Filter Cartridge, 19 Sq Ft, 4-5/8 x 8 In., Replacement for Unicel 4CH-21, Pleatco PTL18P4, Filbur FC-0121

Compatible with Unicel

4CH-21

Hot Tub Filter Cartridge, 19 Sq Ft, 4-5/8 x 8 In., Replacement for Unicel 4CH-21, Pleatco PTL18P4, Filbur FC-0121

Also sold as

20245-238FC-0121FC-0136PTL18P4PVT 25N

Your number not here? Send it to us and we'll confirm the match.

OEM numbers listed for fitment identification only.

Specifications

Compatible brandUnicel
CategoryHot Tub & Spa Filters
Lead time15–25 days after order confirmation
  • MOQ 50 pcs · samples from 1
  • Private label available
  • Ships from our factory

Request wholesale quote

or

One request covers the whole list — no need to send them one by one.

Tiered pricing available above 1,000 pcs · OEM packaging available

Product overview

4CH-21 is an aftermarket pleated hot tub filter cartridge, 4-5/8 in. in diameter and 8 in. long, with 19 sq ft of filter area. Top: molded cone handle. Bottom: 1-1/2" male thread/MPT.

It interchanges with Pleatco PTL18P4, Filbur FC-0121, Filbur FC-0136.

Pleatco lists PTL18P4 as discontinued in its 2025-26 catalog. This cartridge keeps the original 4-5/8 x 8 in. size, so it drops into the same filter housing.

OEM cartridges it replaces: Saratoga Spas 20245-238; Vita Spas PVT 25N.

Fitment notes: Dream Maker Spas: Remove "pad adaptor" (if present) from skimmer before threading MPT directly into suction fitting; 2000 to present w/LED lights. Replaces any cartridge that has an MPT fitting or a 1.9" id w/ disposable adapter. Vita Spas: Remove "pad adapter" from the skimmer before threading Unicel MPT directly into the suction fitting.

Before ordering, measure the old cartridge — overall length, outside diameter and both end fittings. Some catalogs quote the length of threaded top-load cartridges with the thread and some without, so a quarter-inch difference between listings is common. We supply spa service companies, dealers and online retailers: MOQ 50 pcs per part, mixed cartons welcome, and single samples to confirm fit before a production order.

Fits these systems

Hot tubs and spas from Alcove, Atera Spas, Dream Maker Spas, Pageant Spas, Saratoga Spas, Vita Spas.

Not sure it fits? Send us a photo of your part and we'll confirm. Send a photo

Sourcing questions

What OEM numbers does 4CH-21 replace?

POOLPOINT 4CH-21 is an aftermarket replacement cross-referenced to 20245-238, FC-0121, FC-0136, PTL18P4 and PVT 25N. Those numbers identify fitment only — the part is manufactured by POOLPOINT, not by Unicel.

Is 4CH-21 a genuine Unicel part?

No. POOLPOINT manufactures compatible aftermarket replacement parts. We are not affiliated with, sponsored by or endorsed by Unicel; the brand name and OEM numbers are used to identify fitment only.

What is the minimum order quantity for 4CH-21?

MOQ is 50 pcs per part, and mixed cartons are welcome to reach the order minimum. Samples are a separate case — we supply single pieces so you can confirm fitment before committing to a production run.

Factory directWe manufacture ourselves. No trading company in between.
Built to lastEngineering materials matched to OEM specs or better.
Cross-referencedEvery part mapped to the OEM numbers it replaces.
Bulk & container supplyMOQ from 50 pcs. Mixed cartons welcome.
3D fitment modelsVerify threads and ports before you commit.

4CH-21

Hot Tub Filter Cartridge, 19 Sq Ft, 4-5/8 x 8 In., Replacement for Unicel 4CH-21, Pleatco PTL18P4, Filbur FC-0121

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