Home › Caldera › C-8300 cartridge (OEM 74817)
Caldera OEM 74817 spa filter (C-8300)
Listed for: Caldera (Watkins) — unverified
Fits Caldera OEM 74817 unverified
Ø 8"L 16-1/2"100 sq ft| Unicel | C-8300 |
|---|---|
| Pleatco | not found in source |
| Filbur | not sourced |
| Top | 3-1/8" / open w/ molded gasket |
| Bottom | 3-1/8" / open w/ molded gasket |
Retailer search links — see disclosure. Verify dimensions before ordering.
How to confirm this is your filter
Pull your current cartridge and measure it end to end, including any handle, and across the widest point of the pleats. This cartridge measures 8" in diameter and 16-1/2" long, with a 3-1/8" / open w/ molded gasket on top and a 3-1/8" / open w/ molded gasket on the bottom. The bottom fitting matters most: a cartridge with the right diameter but the wrong thread or open-end size will not seal in the filter housing, letting unfiltered water bypass the media.
The 100 sq ft rating describes the pleated media area. Caldera housings are designed around a particular cartridge, so choose a replacement with the same size and fittings rather than a larger area rating. We did not find a Pleatco equivalent for C-8300 in the Pleatco 2023 cross-reference, so search by the Unicel or OEM number.
Similar-diameter Caldera cartridges
- C-8399 cartridge (OEM 1039607) — 8" × 16-1/2"
⚠ Unverified / possible conflict: this row has not been fully confirmed against a second source. Gaps: no Pleatco equivalent found in Pleatco 2023 xref p.43; no Filbur equivalent sourced; no model-year range in source. Measure your old cartridge before ordering.
Sources
- Unicel 2026 Replacement Guide — OEM Cross Reference, PDF p.29; spec table PDF p.19 (PDF)