POOLPURE PWK35B Spa Filter Replacement — 35 sq ft, 50-Micron Trilobal, Fits Watkins/Hot Spring (14-1/8" x 2")

The POOLPURE PWK35B is a direct-fit replacement spa filter with 35 sq. ft. of trilobal filtration fabric and 50-micron fine filtration for clearer spa water.

Designed as a compatible upgrade for many Hot Spring and Watkins spa models, this POOLPURE cartridge balances heavy-duty construction with a high-efficiency media to trap fine particles and simplify maintenance. Built to OEM-fit dimensions—14 1/8" length with 2" open top and bottom—this filter swaps into place easily and uses trilobal fiber and a dirt-locking structure to hold more debris between cleanings.

How does this filter improve spa water clarity?

The PWK35B uses a trilobal filtration fabric that increases surface area compared with conventional fibers, capturing more sediment and finer particles. A dedicated 50-micron layer traps hair, dust, sand, and small organic matter so your circulation system sends back cleaner water.

• 35 sq. ft. of media for larger dirt-holding capacity
• 50-micron fine filtration to reduce visible particulates
• Trilobal fiber structure for increased adsorption area
• Dirt-locking design helps prevent re-release during normal flow

Will it fit my Watkins or Hot Spring spa?

The cartridge measures 14 1/8" long with 6 3/8" outer diameter and 2" open top and bottom ports, matching the common PWK35B and Watkins 1642301-1 footprint. POOLPURE lists compatibility with multiple OEM and aftermarket part numbers so you can compare dimensions and install without modification.

• Direct replacement for Watkins 1642301-1, 78161, 78286
• Compatible with Hot Springs Limelight series and similar models
• Also cross-references Pleatco PWK35B, Filbur FC-3921, Unicel C-6350
• Check your spa’s existing filter dimensions before purchase

How durable and easy to maintain is the cartridge?

POOLPURE built this cartridge with reinforced ABS end caps, a strengthened core, and thickened 4 oz. polyester media for extended life. The patented dirt-locking structure releases trapped debris easily during rinsing, making routine cleaning quicker and more effective.

• Reinforced construction lasts roughly 30% longer than standard cartridges
• Simple rinse-and-reuse maintenance reduces replacement frequency
• Patented dirt-locking reduces repeated clogging and cleaning time
• NSF/ANSI 50-tested materials ensure safety in long-term water exposure

What certifications and real-world validations support performance?

POOLPURE cartridges are tested to NSF/ANSI 50 standards for material safety, and the brand participates in industry organizations to align with recognized filtration practices. The company also highlights field use with competitive swim programs and athlete endorsements to demonstrate reliable performance in demanding environments.

• NSF/ANSI 50 material-safety testing via IAPMO
• Member of the Pool & Hot Tub Alliance (PHTA)
• Field-tested in aquatic training and recognized by media partners
• Designed to meet OEM fit and filtration expectations

Who is this for? If you own a Watkins, Hot Spring Limelight, or any spa that accepts a 14 1/8" x 6 3/8" cartridge and you want an NSF-tested, longer-lasting replacement that captures finer particles, the POOLPURE PWK35B is a practical choice. It's suited to homeowners and maintenance pros seeking an affordable compatible filter with easy maintenance, stronger construction, and better dirt-trapping performance than many basic cartridges.