Unicel 7CH-975 Replacement Spa Filter Cartridge – 7″ OD x 10-1/2″ Length, 1-1/2″ SAE Threaded Bottom (Dimension One Style)
The Unicel 7CH-975 is a replacement spa filter cartridge commonly used in Dimension One and similar hot tub filtration systems that require a 7″ diameter cartridge with a semi-circular top handle and a 1-1/2″ SAE threaded bottom connection. Replacing a worn cartridge helps restore circulation, improve water clarity, and reduce strain on spa pumps and heaters.
Key Features
- Threaded bottom connection: 1-1/2″ SAE (coarse thread) for secure fit in compatible filter canisters
- Top handle: semi-circular handle for easy removal and servicing
- Durable pleated media designed for repeated rinsing and deep-clean cycles
- Helps capture fine debris for clearer water and more consistent flow
Specifications
- Part Number: 7CH-975
- Outside Diameter: 7″
- Length: 10-1/2″ (end cap to end cap; excludes handle/threads beyond end caps where applicable)
- Top End Cap: Semi-circular handle
- Bottom End Cap: 1-1/2″ SAE thread (coarse)
- Pleat Count (approx.): 216
- Filtration Area: commonly listed around 52 sq ft (some spa catalogs group this size as a “75 sq ft” class; match by measurements and end style)
Replaces / Cross References
- Dimension One: 1561-12
- Pleatco: PDO75P3
- Filbur: FC-0475
- Other common references: 17527, 70522
When to Replace
- Water stays cloudy or circulation feels weak even after cleaning
- Pleats are torn, frayed, flattened, or separating from the end caps
- Filter is difficult to rinse clean or quickly plugs up after cleaning
- End caps or threaded connection are cracked/warped and won’t seal properly
Installation Notes
- Turn off power to the spa before removing the filter.
- Thread the cartridge in by hand until it seats; do not overtighten.
- If your system uses an O-ring or sealing gasket at the housing, inspect and replace if flattened or cracked.
Related Products
- Unicel 7CH-975 (Shop / Options)
- Filbur FC-0475 (Alternate)
- Pleatco PDO75P3 (Alternate)
- Spa Cartridge Filter Cleaner
- Cartridge Cleaning Wand
- Spa Water Test Strips
Maintenance Tips
- Rinse the cartridge regularly (often weekly with heavy use) to prevent restriction and keep flow strong.
- Deep clean every 3–6 weeks with a cartridge cleaner to remove oils; rinse thoroughly before reinstalling.
- If scale is present, degrease first, then treat for scale (never reverse the order), and rinse completely.
- Rotating between two cartridges (one in use, one drying after cleaning) can extend filter life and improve overall performance.
