Which filter does my Hot Spring hot tub take? Lookup by model and year

Reviewed October 25, 2026

The dealer fitment table lists six Hot Spring factory cartridge numbers across these collections: 71825 (pleated, 6" × 10-1/2"), 71827 (8-1/2" × 10-1/2", 65 sq ft), 79435 (Tri-X), 78161 (Limelight 2018 and newer), 78286 (Limelight Prism) and 77004 (Limelight Gleam). The same model name can change cartridge by year, for example Limelight Flair and Pulse take the 71827 for 2008–2017 and the 78161 for 2018–2026. Find your model below, then confirm against the part number on your old cartridge.

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The cartridges, with equivalents

Equivalents and sizes are from the Unicel 2026 Replacement Guide unless the table says otherwise. A part number in brackets is another factory number for the same cartridge in Unicel’s cross-reference.

Find your model

Rows show the factory part number, then the model years it is listed for. Where two part numbers are joined by “or”, the dealer table lists both for those years. Years are from one dealer’s table and are the least certain part of this page; the part number on your old cartridge wins.

Highlife

Limelight

Hot Spot

Tiger River

Solana

Highlife: pleated cartridge or Tri-X?

For many Highlife models the dealer table lists both the pleated 71825 and the Tri-X 79435 over the same years. The dealer’s note says to use the pleated cartridge only where the spa specifies 71825 or its listed equivalent, and that models requiring Tri-X must use a Tri-X filter. Hot Spring’s own filter article says its Tri-X is compatible with all Highlife Collection models, including those that did not come with one as standard, and gives replacement intervals of 2–3 years for polyester cartridges and 4–6 years for Tri-X. If your spa came with Tri-X cartridges, stay with Tri-X.

Where the dealer tables differ

Model-year ranges are not identical between dealers. For the Aria, this page’s main source lists Aria AR for 2007–2018, while another Hot Spring dealer’s Tri-X listing gives Aria 2007–2015. Ranges for a model’s first and last year are the least reliable part of any dealer table.

How to confirm yours

1. Read the part number on the old cartridge, or on the filter label if it has worn off.
2. If you cannot read it, measure the diameter and length: a 6" × 10-1/2" cartridge is the 71825 family and an 8-1/2" × 10-1/2" one is the 71827 family. Our filter-size guide shows how.
3. Check how many cartridges your spa takes in your owner’s manual; we do not list counts per model.

Why one cartridge size can carry two different square-foot ratings: our explainer with Unicel’s pleat-count table.

Sources

1. Leisure Time Inc.: Hot Tub Filter Fitment Guide (Hot Spring tables; fetched 2026-10-25)
2. Unicel 2026 Replacement Guide: Hot Springs Spas cross-reference (printed p. 35) and spec tables (pp. 5–8)
3. Pleatco 2023 Catalog: Hot Spring PWK35B entry for OEM 1642301-1
4. Hot Spring Spas: How Do Hot Tub Filters Work? (Tri-X compatibility and replacement intervals)
5. Prisco Hot Spring: 79435 Tri-X listing (size and model-year table)
6. HotSpring World UK: Tri-X 65 sq ft listing

This page summarizes published catalogs and dealer fitment tables; always follow your own spa’s owner’s manual. See our disclaimer and methodology.