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PDC Spas OEM FLT-1000-CART spa filter (4CH-15)
XD1, XD1+ and XD2 cold side
Replacement numbers
Unicel 4CH-15
Fits PDC Spas OEM FLT-1000-CART, 817-0020.
Diameter 4-5/8" (117 mm)Length 5-3/16" (132 mm)15 sq ft1 model listedSearch this part on Amazon
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| Unicel | 4CH-15 |
|---|---|
| Pleatco | not found in source (Not in the Pleatco 2023 Unicel cross-reference (no 4CH-15, no 817-0020).) |
| Filbur | not found in Filbur catalog |
| Top | dual bar handle |
| Bottom | 1-1/2" SAE |
Bottom: 1-1/2" SAE
Drawn to scale from the listed diameter and length. Handles, threads and closed ends are drawn as symbols, not to scale. 15 sq ft media.
XD1, XD1+ and XD2 cold side is the group name on the PDC Spas row 4CH-15 cartridge (OEM FLT-1000-CART). Match these numbers: OEM FLT-1000-CART, 817-0020; Unicel 4CH-15. 4-5/8" across, 5-3/16" long, top dual bar handle, bottom 1-1/2" SAE, 15 sq ft.
Catalog note for FLT-1000-CART: PDC’s 2025 guide: XD1, XD1+ and the XD2 cold side, 2024 to present, FLT-1000-CART, 15 sq ft, 4-5/8" × 5-1/4", 1-1/2" SAE on the bottom, bar handle on a closed top, Waterway 817-0020. Unicel’s Waterway line prints 817-0020 as 4CH-15 at 4-5/8" × 5-3/16", dual bar handle, 1-1/2" SAE, 199 pleats, 3 oz, 15 sq ft. The length differs by 1/16". The dimensions on this row are Unicel’s. Pleatco’s 2023 cross-reference has no 4CH-15 and no 817-0020. Filbur’s PDC section does not list it. The XD2 spa side is FLT-171-CART, not this cartridge.
4CH-15 (OEM FLT-1000-CART), Pleatco side: Not in the Pleatco 2023 Unicel cross-reference (no 4CH-15, no 817-0020)..
FLT-1000-CART, Filbur note: Not in Filbur’s PDC Spas section (printed p.45)..
PDC Spas applications recorded for this cartridge: XD1, XD1+ and XD2 cold side, years 2024 to present, listed by PDC Spas Common Replacement Filter Elements (2025) (FLT-1000-CART / Waterway 817-0020. Not the open XD2 spa-side cartridge.).
Hold 4CH-15 next to PRB7B differs by no Unicel number, Pleatco PRB7B, 5" diameter, 4-5/8" long, top 2-1/8" / open, bottom 2-1/8" / open, 17 sq ft, OEM FLT-118, note says PDC’s 2025 guide is the only size: Timeless and XTR, 2000–2005, FLT-118, Pleatco PRB7B, 17 sq ft, 5" × 4-5/8", 2-1/8" holes. Pleatco’s 2023 deactivated list prints PRB7B with replacement N/A, and the spec table has no PRB7B row. Unicel’s PDC block lists C-4401 at 35 sq ft, 4-15/16" × 4-5/8", two per set, and does not print FLT-118 or PRB7B. Filbur’s PDC section prints that C-4401 set (FC-2386) and does not print PRB7B. Pleatco does not say PRB7B was replaced by PRB17.5SF-PAIR.; C-4310 differs by Unicel C-4310, Pleatco PWW10, Filbur FC-3077, 4-1/4" diameter, 4" long, top 2-1/16" / open, bottom 2-1/16" / open, 10 sq ft, OEM FLT-101SK, note says PDC’s 2025 guide: Nouveau, 1996–1999, FLT-101SK, 10 sq ft, 4-1/4" × 4", 2-1/16" holes, Pleatco PWW10. Unicel prints the same size for C-4310 (216 pleats, 3 oz, 2-1/16" both ends) and lists it on the PDC block. Pleatco’s cross sends C-4310 to PWW10 and prints PWW10 at 10 sq ft; PWW10PAIR is 20 sq ft and is not this row. Filbur prints FC-3077 at the same outside size with 1-15/16" openings..
Pleatco and Filbur do not have a number on this row. Search FLT-1000-CART or the PDC Spas part you pulled out of the spa.
Left blank on purpose: Length 5-1/4" (PDC) vs 5-3/16" (Unicel). No Pleatco equivalent in the 2023 cross-reference. No Filbur PDC row. Top wording: PDC “bar type handle on closed top”; Unicel “dual bar handle.”.
Where those figures are printed: PDC Spas (manufacturer filter guide, 2025) on 4CH-15 (XD Series, XD1, XD1+ and XD2 cold side, 2024–present: FLT-1000-CART, 15 sq ft, 4-5/8" × 5-1/4", 1-1/2" SAE, bar handle, closed top, Waterway 817-0020). Unicel 2026 Replacement Guide on 4CH-15 (Waterway line: 817-0020 = 4CH-15, 4-5/8" × 5-3/16", 1-1/2" SAE, 199 pleats, 3 oz, 15 sq ft. Spec table PDF p.6 (printed p.2): dual bar handle.).
Hot tubs listed for this cartridge
The rest of the PDC Spas model list is the PDC Spas filter by model and year lookup.
| Model / system | Years | Listed by |
|---|---|---|
| XD1, XD1+ and XD2 cold side (FLT-1000-CART / Waterway 817-0020. Not the open XD2 spa-side cartridge.) | 2024 to present | PDC Spas Common Replacement Filter Elements (2025) |
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. Number formats: how Filbur, Unicel and Pleatco numbers compare.
Other PDC Spas cartridges
- PRB7B cartridge (OEM FLT-118), 5" (127 mm) × 4-5/8" (117 mm)
- C-4405 cartridge (OEM FLT-171-CART), 4-15/16" (125 mm) × 6-5/8" (168 mm)
- C-4310 cartridge (OEM FLT-101SK), 4-1/4" (108 mm) × 4" (102 mm)
- C-4326 cartridge (OEM FLT-201TL), 4-15/16" (125 mm) × 13-5/16" (338 mm)
- 4CH-949 cartridge (OEM FLT-SWIM50-CART), 4-15/16" (125 mm) × 13-1/2" (343 mm)
- C-4975 cartridge (OEM FLT-SWIM75-CART), 4-15/16" (125 mm) × 20-1/8" (511 mm)
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
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Leisure Time O Filter Clean Cartridge Cleaner Listing title: cartridge cleaner, 32 fl oz.
-
SpaGuard Filter Cleaner Listing title: filter cleaner for spas and hot tubs, 1 quart.
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AquaChek SPA 6-in-1 Test Strips Listing title: reads total bromine, total chlorine, free chlorine, pH, total alkalinity and total hardness.
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Sources
- PDC Spas (manufacturer filter guide, 2025): XD Series, XD1, XD1+ and XD2 cold side, 2024–present: FLT-1000-CART, 15 sq ft, 4-5/8" × 5-1/4", 1-1/2" SAE, bar handle, closed top, Waterway 817-0020 (PDF)
- Unicel 2026 Replacement Guide: Waterway line: 817-0020 = 4CH-15, 4-5/8" × 5-3/16", 1-1/2" SAE, 199 pleats, 3 oz, 15 sq ft. Spec table PDF p.6 (printed p.2): dual bar handle. (PDF)
Not in sources: Length 5-1/4" (PDC) vs 5-3/16" (Unicel). No Pleatco equivalent in the 2023 cross-reference. No Filbur PDC row. Top wording: PDC “bar type handle on closed top”; Unicel “dual bar handle.”.