Solana OEM 31489 spa filter (C-6430)

Solana (Hot Spring family)

Replacement numbers

Unicel C-6430, Pleatco PWK30-4

Fits Solana OEM 31489, 71825, 71826.

Diameter 6" (152 mm)Length 10-1/2" (267 mm)30 sq ft4 models listed

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UnicelC-6430
PleatcoPWK30-4
FilburFC-3915
Top1-15/16" (49 mm) / open
Bottom1-15/16" (49 mm) / open
Ø 6" (152 mm)10-1/2" (267 mm)Side view · end views belowTopBottom
Top: 1-15/16" (49 mm) / open
Bottom: 1-15/16" (49 mm) / open
Drawn to scale from the listed diameter and length and open-end sizes. Handles, threads and closed ends are drawn as symbols, not to scale. 30 sq ft media.

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Solana files this cartridge as C-6430 cartridge (OEM 31489), in the Solana (Hot Spring family) group. Numbers on the row: OEM 31489, 71825, 71826; Unicel C-6430; Pleatco PWK30-4; Filbur FC-3915. 6" across, 10-1/2" long, top 1-15/16" / open, bottom 1-15/16" / open, 30 sq ft.

What the sources add about 31489: Unicel does not list Solana separately; Solana model fitment for OEM 71825 is from Leisure Time Inc. Some Hot Spring-family spas use a Tri-X ceramic cartridge with the same footprint instead; Leisure Time Inc.: Use this pleated cartridge only where the spa specifies 71825 or its listed equivalent. Models requiring Tri-X cartridges must use the appropriate Tri-X filter.; Leisure Time Inc.: Replaces compatible 71825 or 31489 pleated cartridges. Models requiring Tri-X cartridges must use the appropriate Tri-X filter. Unicel's 2026 price list (not its spec table, which still prints C-6430 with 4 oz media) says "C-6430 USE C-6430AM", the antimicrobial version (30 sq ft, Watkins replacement).

Model list attached to C-6430 cartridge (OEM 31489): Solana RX, years 2003–2009, listed by Leisure Time Inc. dealer listing; Solana SX, years 2003–2010, listed by Leisure Time Inc. dealer listing; Solana TX, years 2003–2010, listed by Leisure Time Inc. dealer listing; Solana Tx X, years 2000–2002, listed by Leisure Time Inc. dealer listing.

Source locations for this Solana row: Unicel 2026 Replacement Guide on C-6430 (OEM cross reference (Hot Springs Spas section), PDF p.39 (printed p.35); spec table PDF p.12 (printed p.8)). Pleatco 2023 Catalog on C-6430 (Unicel-to-Pleatco cross reference, PDF p.47). Filbur Catalog & Reference Guide on C-6430 (Product by Pool/Spa Manufacturer (OEM), Hot Springs, printed p.38 (PDF p.20)). Leisure Time Inc. (Hot Spring/Caldera dealer) on C-6430 (Compatibility section: model and model-year list). Leisure Time Inc. (Hot Spring/Caldera dealer) on C-6430 (Compatibility section: model and model-year list).

Hot tubs listed for this cartridge

Model / systemYearsListed by
Solana RX2003–2009Leisure Time Inc. dealer listing
Solana SX2003–2010Leisure Time Inc. dealer listing
Solana TX2003–2010Leisure Time Inc. dealer listing
Solana Tx X2000–2002Leisure Time Inc. dealer listing

Other Solana models and years are in the Solana section of the Hot Spring filter by model and year lookup.

Check the cartridge you removed

Measure diameter, length, and both ends, then compare them with the figures above. The steps are in the measuring guide. Why the bottom decides whether it seals: open-end vs threaded filters. Power, the retainer, and not running the spa empty: how to install a cartridge. Brand notes: Hot Spring filter sizes by collection. Number formats: how Filbur, Unicel and Pleatco numbers compare.

The same C-6430 number is also on the Hot Spring, Hot Spot, Caldera pages.

Every number on this row, on one screen: cross-reference lookup. Published clean and replace intervals for this cartridge, and a buy link for the numbers above: replacement schedule and reorder. The interval comparison by brand: calculator.

Cleaner and test strips

Hose rinse and soak steps are in how to clean a cartridge. Named cleaners and strips are in filter cleaners and test strips.

Filter cleaner and test strips

Sources