Unicel 4CH-21 | 19 sq ft Saratoga & Vita Spa Filter
Excluded Brands
The following brands are not eligible for LTI discount codes (including WELCOME). They go on sale only during manufacturer-authorized promotions:
- Gozney — pizza ovens and accessories
- OHCO — massage chairs
- Positive Posture — massage chairs and recliners
- Nomadix — outdoor lifestyle products (towels, blankets, accessories)
Excluded Products
The following individual products are also not eligible for discount codes:
- Any product that already has a price markdown — items on sale or clearance can't stack additional discounts on top
- FreshWater Salt System Replacement Cartridge (single)
- FreshWater Salt System Replacement Cartridge (3 Pack)
- Route Protection Insurance — third-party shipping protection, not eligible for our discounts
- Bullfrog A / R / X Series 10-00282 Filter Cartridges
- Bullfrog STIL Series 10-00281 Filter Cartridges
- FROG® @ease Sanitizer System for Bullfrog Spas
- FROG® @ease Replacement Cartridge for Bullfrog Spas (3 Pack)
- Bullfrog Simplicity™ Flat Filters for M Series (4 Pack)
- Filter Core Cage & Cap Assembly for Bullfrog Spas
- Fireplaces (gas, wood-burning, and fireplace inserts)
- Electric Fireplaces
- Gas Vent Pipe
- Pellet Vent Pipe
- Fireplace Fronts
This list can change. Manufacturers occasionally add or remove products from their MAP-protected lists. We update this page when they do, but the most accurate way to confirm whether a discount applies to a specific item is to add the item to your cart and try the code at checkout. If the code doesn't work, the item is excluded. If it does work, it's eligible.
The Unicel 4CH-21 is a compact 19 square foot top-load replacement cartridge for Saratoga, Vita, Dream Maker, and several other spa brands, replacing OEM part numbers 20245-238 and PVT-25N. At just 8" tall and 4-5/8" across, it is one of the smaller cartridges in the top-load family — and it packs 158 pleats into that short body, a genuinely dense fold count for its size.
The bottom carries a 1-1/2" male pipe thread that screws directly onto the suction fitting in the floor of the skimmer, with a molded cone handle on top for grip. That threaded connection is the design's real strength. On a drop-in cartridge, the seal depends on the filter seating flat against a surface, and any gap lets unfiltered water slip past the media — the reason a spa can run cloudy with a brand-new filter installed. On a threaded top-load, the cartridge is the connection. Water cannot reach the pump without passing through the media, because the only route into the suction line runs through the inside of the cartridge.
It is worth being straight about what 19 square feet means in practice. This is a small cartridge, and small cartridges load faster than large ones. That is not a shortcoming — it is what fits the compact skimmer housings these spas use, and the spas are sized to match. But it does mean the maintenance rhythm here is different from a big-bodied filter. The same bather load spread across 19 square feet reaches the point of restricting flow considerably sooner than it would across 65 or 100. Owners who apply a hot-tub-sized cleaning schedule to a cartridge this size are the ones who find themselves wondering why their jets have gone weak.
Media is Unicel's standard 3 oz Reemay polyester — one hundred percent spunbonded polyester over a solid molded core, with chemical-resistant end caps built to an exact OEM fit. Made in the USA by Meissner Manufacturing, with more than 45 years behind the Unicel name.
Pro Tip: Rinse this cartridge more often than you would a large one — every two weeks is a better default here than every four. Capacity and cleaning interval are directly linked, and a 19 square foot filter simply reaches the point of restricting flow sooner than a big-bodied cartridge carrying the same load. Keeping a second cartridge to rotate pays off faster on a small filter than on a large one, too: you swap in the clean one in under a minute, let the other dry completely, and the dried cartridge sheds trapped debris far more easily at the next rinse.
UNICEL®
UNICEL® Brand FAQs
Who makes Unicel filters?
Unicel filters are made byMeissner Mfg. Co., Inc., a family business that began as a small contract sewing operation in thelate 1950sand moved into pool filtration through the 1970s. By the end of that decade the company was producing cartridge filters for the industry'soriginal equipment manufacturers, and in1985it introduced the Unicel brand as aftermarket replacements. It's still owned and operated by the Meissner family today.
Are Unicel filters as good as the original manufacturer's filter?
Unicel builds its cartridges tomeet or exceed original equipment specifications— and that's a meaningful distinction here, because the company produced cartridges for the industry's OEMs before it ever launched its own brand. Unicel cartridges usedurable, chemical-resistant end capswith an exact fit,high-capacity media,uniform pleatsfor optimal flow, and asolid corethat resists collapsing under pressure.
Where are Unicel filters made?
Unicel filters are manufactured inCalifornia, with components sourcedexclusively in the United States. The line comprisesnearly 500 products, covering replacement cartridges, D.E. grids, filter discs, and related parts.
How do I find the right Unicel filter for my spa?
Unicel cartridges areinterchangeable with all major filter brands, and each one cross-references to a list of original equipment part numbers. The most reliable method is topull your current cartridge and read the part number printed on it, then match it to the Unicel cross-reference. If the number has worn off,measure your old cartridge— diameter, length, and the size and style of the openings at each end — and match those instead. Also confirmhow many cartridgesyour spa uses.
How long does a Unicel filter last?
Cartridge life depends on how heavily the spa is used, yourwater chemistry, and how consistently you clean the filter. Many Unicel cartridges useReemay® polyester media, whosetrilobal fibersprovide considerably more surface area than standard rounded fibers — which increases dirt-holding capacity and extends the time between cleanings. With regular rinsing and periodic deep cleaning, a well-maintained cartridge commonly serves a year or more.
When should I replace my filter instead of cleaning it?
Replace the cartridge when thecycle between cleanings becomes noticeably shorter, when you seelow water flowor high differential pressure, when the media has atear, or if thecenter core collapses. Pleats that stay permanently flattened or discolored after a proper cleaning are another sign the cartridge has reached the end of its service life.
About UNICEL®
Unicel is the nation's leading manufacturer of replacement filter cartridges for pools and spas — and the story behind it is a genuinely American one. In the late 1950s, Richard T. Meissner started a small part-time contract sewing operation. Through the 1970s, Meissner Mfg. Co., Inc. moved into swimming pool filter bags, then D.E. grid element covering, and by the end of that decade the company was producing cartridge filters for the industry's original equipment manufacturers.
That's the detail that matters most: Unicel was building the filters that went into new spas long before it sold a replacement. In 1985, the company introduced the UNICEL brand so dealers and technicians could source elements built to O.E.M. specifications from a single place — even for equipment brands they didn't carry. Today the line spans nearly 500 products, all manufactured in California with components sourced exclusively in the USA.
By staying focused on one thing — filtration — Unicel has built deep expertise in a critical corner of the industry, from media development to cartridge design. Every cartridge is built with chemical-resistant end caps for an exact fit, high-capacity filter media, uniform pleats for optimal flow, and a solid core that holds its shape under pressure. Meissner Mfg. Co., Inc. remains owned and operated by the Meissner family, still recognized for quality and service. American-made products, world-class service.
