Unicel C-7350 | 50 sq ft Caldera Spa Filter

By Unicel
SKU: C-7350
$69.99

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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-7350Ā deliversĀ 50 square feetĀ of filtration built onĀ ReemayĀ® polyester media, capturing debris down to an average ofĀ 20 microns. Built toĀ meet or exceed OEM specifications, it's the replacement cartridge forĀ new-style CalderaĀ® Spas, taking the place of Caldera partsĀ 73532Ā andĀ 1019401.

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.

What separates a Unicel from a bargain cartridge is the media itself.Ā ReemayĀ uses aĀ trilobalĀ fiber — three-lobed in cross-section rather than round — which delivers roughlyĀ 45% more surface areaĀ than standard rounded filter fibers. More surface means more places to capture dirt and oils, higher dirt-holding capacity, andĀ more time between cleanings. Add aĀ semi-circular handleĀ for easy lifting, aĀ 2-11/16 inch open bottomĀ that seats into the housing, andĀ chemical-resistant end caps, and you get a cartridge built to last. Made in the USA.

Pro Tip:Ā This is the "new style" Caldera cartridge — verify yours before ordering. Caldera has used several cartridge designs and sizes across its model years, and this one covers the configuration with aĀ handle on top, a 2-11/16 inch open bottom, and a 7 by 10-3/4 inch body. If the numbersĀ 73532Ā orĀ 1019401Ā appear on your current filter, you're in the right place.

Brand

UNICELĀ®

Key Features
  • 50 sq ft of filtration — full OEM-spec filtration area
  • 45% more surface area — Reemay trilobal fibers outperform standard rounded fibers
  • Captures down to 20 microns — removes particles far finer than the eye can see
  • Direct Caldera replacement — takes the place of parts 73532 and 1019401
  • Semi-circular handle — makes removal and cleaning effortless
  • 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 back and forth packsĀ 50 square feetĀ of filtering surface into a cartridge 7 inches across and 10-3/4 inches tall. More surface means water passes throughĀ more slowly and thoroughly, capturing finer particles, and it means the filter holds far more debris before flow starts to drop off.

The fiber shape is whereĀ ReemayĀ earns its reputation. Standard filter fibers are round; Reemay's areĀ trilobal, and that three-lobed cross-section packs roughlyĀ 45% more surface areaĀ into the same amount of material. More surface per fiber means more places for dirt to be trapped, and theĀ smooth media surfaceĀ releases that dirt readily when you rinse it. Just as important is theĀ fit: Unicel engineers its cartridges to the original manufacturer's exact dimensions, producing a tight seal in the housing so water is forcedĀ throughĀ the media rather than around it.

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. Seat the new cartridge squarely in the filter well, fully seated so the open bottom engages the housing connection properly.
  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: Keep a spare cartridge in rotation. A proper chemical soak takes hours, and the filter cleans best when it can dry completely afterward — awkward when your spa needs it back right away. With a second cartridge you can drop in a clean one immediately and service the other on your own schedule, so your spa never runs on a dirty filter and both last longer.

Specifications
  • Brand:Ā Unicel (Meissner Mfg. Co., Inc.)
  • Part Number:Ā C-7350
  • Series:Ā Unicel 7000 Series
  • Product Type:Ā Replacement spa filter cartridge
  • Filtration Area:Ā 50 sq ft
  • Pleat Count:Ā 200
  • Filtration Rating:Ā Captures debris to an average of 20 microns
  • Media:Ā Reemay spunbonded trilobal polyester, 3 oz basis weight
  • Outer Diameter:Ā 7 in
  • Length:Ā 10-3/4 in
  • Top:Ā Semi-circular handle
  • Bottom:Ā Open, 2-11/16 in inner diameter
  • End Caps:Ā Durable plastic, chemical-resistant, exact OEM fit
  • Fits:Ā Caldera Spas (Watkins Mfg.) — new style
  • Replaces OEM:Ā Caldera Spas 73532, 1019401
  • Cross-References:Ā Pleatco PCD50N, Filbur FC-3963, 735321
  • 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: 7"
  • Length: 10-3/4"
  • Semi-circular handle
  • 2-11/16" opening
  • Pleat Count: 200
  • Media: 3 oz.
  • Filtration Square Footage: 50 sq. ft
Compatibility

The C-7350 is built forĀ new-style CalderaĀ® SpasĀ (Watkins Mfg.) systems. It serves as a direct replacement for these OEM cartridges:

  • Caldera Spas:Ā 73532, 1019401

It's also cross-referenced asĀ Pleatco PCD50N,Ā Filbur FC-3963, andĀ 735321.

Before ordering, verify theĀ end configuration — semi-circular handle on top, 2-11/16 inch open bottom — along with the 7 inch diameter and 10-3/4 inch length, since Caldera offers cartridges in several 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 Ravello 2022-Current
  • Paradise Kauai 2000-Current
  • Paradise Martinique 2000-Current
  • Paradise Makena 2024
  • Highland Cascade 2000-2001
  • Highland Cumberland 2002-2009
  • Highland San Gabriel 2008-2009
  • Highland Teton 2000

This is a replacement for the Caldera Paradise 73532 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.