Unicel C-8327 | 125 sq ft Sundance Spa Filter

• 125 square feet of filtration area: The largest capacity in the Unicel spa range, clogging slowly, holding flow steady between cleanings, and substantially reducing strain on the circulation pump.
• 199 pleats across a full 19" height: Generously spaced folds made possible by the cartridge's size, so a hose can reach the base of each pleat and debris rinses free rather than compacting.
• Fits Sundance spas across two decades: One cartridge covers the 980, 880, 780, 850, Select, and Portofino families, spanning model years from 2002 to the present.
• 1-1/2" male slip fitting top: An unthreaded push-fit connection that cannot be cross-threaded or stripped, making repeated removal for cleaning faster and safer than on a threaded cartridge.
• Open 2-1/2" beveled bottom: The beveled edge guides the cartridge into correct alignment as it seats and helps form a proper seal against the well.
• 3 oz Reemay 2033 media: Spunbonded one hundred percent polyester with strong chemical resistance, balancing dirt-holding capacity against cleanability so the cartridge recovers well through repeated wash cycles.
• Approximately 20-micron filtration: Captures the fine suspended particles responsible for cloudy, hazy water.
• Solid injection-molded core: Runs the full 19" length to hold pleat geometry and resist the flexing that a cartridge this tall would otherwise be prone to.
• Made in the USA: Manufactured by Meissner Manufacturing to meet or exceed OEM specification.

The cartridge stands in the filter well with its beveled bottom seated over the fitting below and its slip fitting engaged in the socket above. When the circulation pump runs, it draws water out through the core, dropping the pressure inside below that of the surrounding spa water. That difference pushes water inward through the pleated media from every direction at once — across the full 8-7/16" circumference and the entire 19" height — and filtered water collects in the core and exits into the suction plumbing.

The slip fitting seals differently from a thread, and the distinction matters. A threaded connection pulls two parts together mechanically, tightening as you turn it. A slip fit relies purely on close tolerance — the outside diameter of the male fitting is machined to match the socket so precisely that the contact between them leaves no meaningful path for water. There is no clamping force involved at all. The seal is created by how well the two surfaces match, which is why debris caught between them is more than a nuisance: it physically holds the surfaces apart, and there is no tightening force available to crush it out of the way.

Having connections at both ends is what allows a cartridge this large to run without a supporting frame, but it also doubles the number of places alignment can go wrong. A cartridge can seat convincingly at the bottom while the slip fitting at the top is only partly engaged, or the reverse. Either way the result is the same: a gap somewhere in the flow path that lets water reach the pump without passing through the media.

Debris loads into the depth of the polyester fibers rather than sitting on the surface, which is why a cartridge that still looks reasonably clean can already be measurably restricted. On a spa this size, declining jet pressure is the most reliable early signal that a cleaning is due.

Pro Tip: Because this cartridge connects at both ends, lower it in straight and check both ends before you close the lid. At 19" tall it is long enough that a small tilt at the top translates into real misalignment at the bottom, and it is easy to feel the bottom seat, assume you are done, and leave the slip fitting at the top only partly home. Wipe the slip fitting and its socket clean before installing — with no clamping force to crush an obstruction out of the way, a single hair caught there opens a bypass path. Then press straight down without twisting, and confirm the cartridge stands vertical rather than leaning. If it will not go fully home, stop and look for debris rather than forcing it.

Installation

1. Turn the spa off at the breaker before opening the filter compartment.
2. Remove the filter lid and lift the old cartridge straight up to withdraw the slip fitting from its socket. If it resists, rock it gently side to side rather than twisting or yanking.
3. Let it drain as you lift. A loaded 125 sq ft cartridge holds a great deal of water and debris, and pulling it out quickly dumps that load back into the well.
4. Note how high the old cartridge sat — that height is your reference for confirming the new one is fully seated.
5. Inspect the well and both fittings. Clear away hair, grit, and scale, and check that the slip socket's inner surface is smooth and unscored.
6. Wipe the slip fitting on the new cartridge clean. Even packaging dust is worth removing.
7. Lower the cartridge in straight, seating the beveled bottom over the lower fitting first, then press straight down with firm, even pressure until the top slip fitting bottoms out. Do not twist.
8. Confirm the cartridge stands vertical, does not rock, and sits at the same height as the old one.
9. Replace the lid, restore power at the breaker, and run a full circulation cycle. Verify normal jet pressure and flow.

Routine Cleaning

• Every 2 to 4 weeks: Remove and rinse with a garden hose. Spray downward into the pleats at an angle, rotating steadily so the full circumference and all 19" of height get direct attention. This is a large cartridge and a thorough rinse takes real time — the lower third collects the heaviest load and deserves the most of it.
• Every 3 months: Deep-soak in a dedicated spa filter cleaning solution to dissolve body oils, lotion residue, and mineral scale that rinsing cannot remove. Rinse thoroughly afterward — cleaner residue left in the media is a common and entirely preventable cause of foaming.
• Inspect the slip fitting at every cleaning. Run a fingertip around it. The surface should feel smooth and unbroken. Scoring, gouges, hardened scale, or a chalky texture all mean the sealing tolerance has been compromised.
• At every drain and refill: Deep-clean the cartridge and clear out both fittings before either goes back into service.
• Rotate two cartridges if you can: A spare lets you install the clean one immediately while the other dries completely. A fully dried cartridge releases trapped debris far more easily on the next rinse, and rotating roughly doubles the useful life of both.

Important Cautions

• Do not use a pressure washer. High-pressure spray tears media fibers and destroys pleat geometry, often without visible damage, and torn media passes unfiltered water straight through.
• Do not twist the cartridge into or out of the slip socket. Slip fittings seal by surface tolerance, and twisting scores that surface permanently.
• Do not use lubricant, sealant, or plumber's tape on the slip fitting. It is designed to seal dry, and these products attract grit that then holds the surfaces apart.
• Do not clean with dish soap, laundry detergent, or household cleaners. These leave residues that foam persistently and are difficult to rinse out.
• Do not run the spa without a cartridge installed, even briefly. Debris drawn directly into the pump can cause damage costing far more than a filter.
• Do not force a cartridge that will not seat fully. Resistance means debris or misalignment, and forcing it deforms the end caps and creates a permanent bypass path.
• Do not boil, bleach, or machine-wash the cartridge.

When to Replace

Replace the cartridge when you see torn or separated media, cracked or deformed end caps, a soft or collapsing core, pleats that have permanently lost their shape, staining that no longer responds to a deep soak, or a persistent drop in flow that thorough cleaning no longer restores. On this cartridge, pay particular attention to the slip fitting: deep scoring, cracking, chips, or distortion of that surface warrants replacement even when the media still looks perfectly good, because a slip fit that no longer holds its tolerance cannot seal. On a cartridge this tall, also watch for a visible bow or lean when it is stood upright, which indicates the core has begun to soften. Most spa owners under typical use replace every 12 to 18 months.

• Brand: Unicel
• Manufacturer: Meissner Manufacturing Co., Inc.
• Part Number: C-8327 — also produced as C-8326, identical cartridge
• Product Type: Replacement spa filter cartridge, slip-fit
• Filtration Area: 125 sq. ft.
• Pleat Count: 199
• Filter Media: 3 oz. Reemay 2033 spunbonded polyester
• Micron Rating: Approximately 20 microns
• Outer Diameter: 8-7/16"
• Length: 19"
• Top End Cap: 1-1/2" male slip fitting, unthreaded
• Bottom End Cap: Open, 2-1/2" inner diameter, beveled edge
• Core: Solid injection-molded, full-length
• End Cap Material: Chemical-resistant molded plastic, exact OEM fit
• Replaces OEM: Sundance Spas 6540-488, 6540-505, 6473-165, 17-175-3230
• Cross-References: Unicel C-8326, Pleatco PSD125-2000, Filbur FC-2780, Aladdin 22507, Baleen AK-70013, Magnum SU125, Darlly 81252, Excel XLS-831
• Fits: Sundance 980, 880, 780, 850, Select, and Portofino Series; Sweetwater and Suntub spas on the same housing
• Quantity Per Spa: One
• Typical Service Life: 12 to 18 months with routine cleaning
• Cleaning Method: Hose rinse every 2 to 4 weeks; chemical soak every 3 months. Do not pressure wash.
• Installation: Press straight down to seat both ends. Do not twist, and do not lubricate the slip fitting.
• Origin: Made in the USA
• Shipping: Standard ground; not classified as a hazardous material

Replaces These OEM Part Numbers

• Sundance Spas 6540-488
• Sundance Spas 6540-505
• Sundance Spas 6473-165
• 17-175-3230

Cross-Reference Part Numbers

• Unicel C-8326 — the same cartridge under a different Unicel number
• Pleatco PSD125-2000
• Filbur FC-2780
• Aladdin 22507
• Baleen AK-70013
• Magnum SU125
• Darlly 81252
• Excel XLS-831

Fits These Sundance Models

Current Series:

• 980 Series — 2017 to present
• 880 Series — 2009 to 2023
• 780 Series — 2007 to 2025

Select Series:

• Constance — 2011 to 2018
• Victoria — 2011 to 2018

880 Series (2005–2008):

• Maxxus, Cameo, and Optima — 2005 to 2008
• Altamar, Majesta, Marin, and Capri — 2006 to 2008

850 Series (2002–2005):

• Maxxus, Cameo, and Optima — 2002 to 2004
• Altamar, Majesta, Marin, and Capri — 2002 to 2005

780 Series (2006):

• Bahia, Cayman, and Palermo — 2006

780/850E Series and Portofino:

• Caprio and Caprio ST — 2002 to 2007
• Tango — 2002 to 2003

Sweetwater Spas and Suntub models built around the same filter housing also use this cartridge.

How to Confirm Fitment

• Top: A 1-1/2" male slip fitting — smooth and unthreaded. Visible threads mean a different cartridge.
• Bottom: Open, 2-1/2" inner diameter, with a beveled edge.
• Overall length: 19", measured end cap to end cap.
• Outer diameter: 8-7/16".

Pro Tip: If the cartridge you are replacing is marked C-8326, you are in the right place. Unicel produces this cartridge under two part numbers — C-8326 and C-8327 — and they are the same filter with identical dimensions, capacity, pleat count, and fittings. The C-8326 number is the one that appears most often on packaging and in cross-reference charts, so it is the one most owners will find on an old cartridge or in a manual. Either number gets you the correct part. The same applies to the aftermarket equivalents listed above: PSD125-2000, FC-2780, and 81252 all describe this same cartridge.