Unicel C-8399 | 100 sq ft Caldera Spa Filter

By Unicel
SKU: C-8399
$89.99

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Check out the Filter Guide to see if this filter fits your hot tub model.

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Description

TheĀ Unicel C-8399Ā is aĀ large-capacityĀ spa filter cartridge deliveringĀ 100 square feetĀ of filtration acrossĀ 259 pleatsĀ ofĀ ReemayĀ® 2033 polyester media, capturing debris down to an average ofĀ 20 microns. Built toĀ meet or exceed OEM specifications, it's the replacement cartridge forĀ CalderaĀ® Spas, taking the place of Caldera partĀ 1039607.

Filtration is the quiet backbone of clean spa water. Every soak leaves behindĀ body oils, lotions, hair, and fine debris, and the cartridge is what removes all of it before it clouds the water, feeds bacteria, or coats your plumbing. When a filter is worn or clogged, the effects spread everywhere: dull water, higher chemical use, softer jets, and aĀ pump and heater strainingĀ against restricted flow.

This is a serious cartridge — 16-1/2 inches tallĀ with a fullĀ 100 square feetĀ of filtering surface packed intoĀ 259 pleats, one of the highest pleat counts Unicel makes. That capacity is exactly what a large, jet-heavy Caldera spa demands. AĀ semi-circular handleĀ molded into the top makes lifting it out effortless, while theĀ 3-5/8 inch open bottom with a lip sealĀ seats into the housing for a positive, leak-free connection. Add Reemay's trilobal fibers andĀ chemical-resistant end caps, and you get a cartridge built to perform through cleaning after cleaning. Made in the USA.

Pro Tip:Ā Pay attention to the lip seal on the bottom end cap. That molded seal is what forces water to travelĀ throughĀ the pleats rather than slipping around the edge of the cartridge — and it's easy to compromise. Make sure the bottom seats squarely and completely in the housing when you install it, and check the seal for nicks or distortion whenever you clean the filter. A cartridge that isn't sealing properly filters far less than its rating suggests.

Brand

UNICELĀ®

Key Features
  • 100 sq ft of filtration — large-capacity, full OEM-spec filtration area
  • 259 pleats — one of the highest pleat counts in the Unicel spa lineup
  • Captures down to 20 microns — removes particles far finer than the eye can see
  • Semi-circular handle — makes removal and cleaning effortless
  • 3-5/8 in open bottom with lip seal — positive, leak-free seating in the housing
  • Made in the USA — built to meet or exceed OEM standards
How It Works

Water is drawn through the cartridge's pleated media as your spa circulates.Ā Pleating creates the capacity: folding the fabric into 259 pleats packs a fullĀ 100 square feetĀ of filtering surface into a cartridge 8 inches across and 16-1/2 inches tall. All that surface means water passes throughĀ more slowly and thoroughly, capturing finer particles, and it means the filter holds a great deal of debris before flow starts to drop off.

The media does the rest.Ā ReemayĀ fibers areĀ trilobal — three-lobed in cross-section rather than round — which packs considerably more surface area into the same material, giving more places for dirt to be captured and a smooth surface that releases it readily when rinsed. Just as important is theĀ seal: the lip seal on the bottom end cap and the exact-fit dimensions ensure water is forcedĀ throughĀ the media rather than around it. A loose or poorly seated cartridge lets debris bypass the filter entirely, no matter how good the fabric is.

Pro Tip: A clean filter protects your equipment, not just your water. As the pleats load up with body oils, your pump has to work harder against the restriction, and reduced flow across the heater can trigger flow-related errors. Regular rinsing and periodic deep cleaning is the cheapest protection there is for the expensive parts of your spa.

Directions for Use

Installation

  1. Turn off power to the spa at the breaker before servicing the filter compartment.
  2. Open the filter lid and clear any debris from the compartment.
  3. Lift the old cartridge out by its handle, noting its orientation.
  4. Lower the new cartridge in and seat it squarely so theĀ bottom lip seal engages fullyĀ in the housing connection.
  5. If your spa uses more than one cartridge,Ā replace them at the same timeĀ so they wear evenly and flow stays balanced.
  6. Close the lid, restore power, and run the circulation to confirm normal flow.

Routine Cleaning

  1. Every two to four weeks:Ā lift the cartridge out by the handle andĀ rinse gently with a garden hose, working between the pleats from top to bottom. A soft brush cleaning tool helps.
  2. Periodically:Ā soak or treat the cartridge with a dedicated filter cleaner to dissolve the body oils and buildup a rinse can't remove, then rinse it off.
  3. Let it dry fullyĀ before returning it to service whenever possible.

When to Replace

  • The cycle between cleanings gets noticeablyĀ shorter
  • Low water flowĀ or high differential pressure
  • The media has aĀ tear
  • TheĀ center core collapses

Cartridge life depends on routine maintenance and your spa's water chemistry.

Pro Tip: With 259 pleats, this cartridge rewards patient rinsing. A dense pleat count is what gives the filter its 100 square feet of capacity, but it also means the folds sit close together and debris settles deep between them. Working the hose stream slowly down each pleat, all the way around, removes far more than a quick pass over the outside — and it noticeably extends how long the cartridge lasts before it needs replacing.

Specifications
  • Brand:Ā Unicel (Meissner Mfg. Co., Inc.)
  • Part Number:Ā C-8399
  • Series:Ā Unicel 8000 Series
  • Product Type:Ā Replacement spa filter cartridge
  • Filtration Area:Ā 100 sq ft
  • Pleat Count:Ā 259
  • Filtration Rating:Ā Captures debris to an average of 20 microns
  • Media:Ā Reemay 2033 spunbonded polyester, 3 oz basis weight
  • Outer Diameter:Ā 8 in
  • Length:Ā 16-1/2 in
  • Top:Ā Semi-circular handle
  • Bottom:Ā Open with lip seal, 3-5/8 in inner diameter
  • End Caps:Ā Durable plastic, chemical-resistant, exact OEM fit
  • Fits:Ā Caldera Spas
  • Replaces OEM:Ā Caldera Spas 1039607
  • Cross-References:Ā Pleatco PCD100W, Filbur FC-3965
  • Cleaning:Ā Rinse gently with a garden hose every two to four weeks; deep clean periodically with filter cleaner. Do not pressure wash.
  • Origin:Ā Made in the USA
  • Shipping:Ā Standard ground; not classified as a hazardous material

  • Outer Diameter: 8"
  • Length: 16-1/2"
  • Top End Cap: semi-circular handle
  • Bottom End Cap: 3-5/8" / open w/ lip seal
  • Pleat Count: 259
  • Media: 3 oz.
  • Filtration Square Footage: 100 sq. ft
Compatibility

The C-8399 is built forĀ CalderaĀ® SpasĀ systems. It serves as a direct replacement for:

  • Caldera Spas:Ā 1039607

It's also cross-referenced asĀ Pleatco PCD100WĀ andĀ Filbur FC-3965.

Before ordering, verify theĀ end configuration — semi-circular handle on top, 3-5/8 inch open bottom with lip seal — along with the 8 inch diameter and 16-1/2 inch length, since Caldera has used several cartridge sizes across its lineup. Also confirmĀ how many cartridges your spa takes. The surest method is toĀ pull your current cartridge and read the part number printed on it. For upkeep, pair it with a dedicatedĀ filter cleanerĀ for periodic deep cleaning.

  • Utopia Cantabria 2014-Current
  • Utopia Elation 2009-2010
  • Utopia Florence 2018-Current
  • Utopia Geneva GEB 2005-Current
  • Utopia Niagara NIB 2005-Current
  • Utopia Tahitian 2005-Current
  • Aquatic Melodies Aspire 2005-2008
  • Aquatic Melodies Elation 2005-2008

This is a replacement for the Caldera 73722 Filter Cartridge

Most products purchased from our online shop within the last 30 days are eligible for return. Please review our return policy to see the list of items that cannot be returned.

Some major items that are non-returnable:

  • Gift cards
  • Electronics
  • Pumps / Motors
  • Hot Tubs
  • Closeouts
  • Fireplaces
  • Electric Fireplaces
  • Massage Chairs
  • See return policy below for full list of non-returnables.

UNICELĀ® 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 useReemayĀ® 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 UNICELĀ®

UnicelĀ 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,Ā Richard T. MeissnerĀ 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 producingĀ cartridge filters for the industry's original equipment manufacturers.

That's the detail that matters most: Unicel wasĀ building the filters that went into new spas long before it sold a replacement. InĀ 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 spansĀ nearly 500 products, all manufactured inĀ 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 withĀ chemical-resistant end capsĀ for an exact fit,Ā high-capacity filter media,Ā uniform pleatsĀ for optimal flow, and aĀ solid coreĀ that holds its shape under pressure. Meissner Mfg. Co., Inc. remainsĀ owned and operated by the Meissner family, still recognized for quality and service. American-made products, world-class service.