
Waterway Clearwater II Filter Locknut Assembly 550-7500
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Quick overview
- Two pieces in one part The assembly is the locknut plus the threaded retainer ring, supplied together.
- Holds the cartridge down The locknut is what clamps the element into the filter body so water cannot bypass it.
- For Clearwater II Sold as the replacement locknut assembly for the Waterway Clearwater II cartridge filter.
- Top inside diameter 15-11/16 inches Measure the old assembly against this before ordering.
- Bottom inside diameter 16-7/8 inches The second dimension to check, since the two ends are not the same.
- No special tools It threads into place with the filter open, using nothing beyond what a cartridge change already needs.
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Frequently bought together

Clearwater II Filter Locknut Assembly 550-7500
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Product details
The Waterway 550-7500 is the filter locknut assembly for the Clearwater II cartridge filter. It comes as two matched pieces, a locknut and a threaded retainer ring, which is how the filter holds the cartridge in place.
Why it matters
The locknut assembly is the clamp that keeps the element seated in the filter body. If it is cracked, stripped or missing, the cartridge can lift or sit off center, and water takes the easy route around the media instead of through it. The filter keeps running and the pool keeps getting dirty, which makes this an easy fault to blame on the cartridge.
Check the dimensions
The top inside diameter is 15-11/16 inches and the bottom inside diameter is 16-7/8 inches. The two ends are deliberately different, so measure both against your old assembly rather than assuming from a photo.
It fits without special tools, in the same access you already have when the filter is open for a cartridge change.
| Brand | Waterway |
|---|---|
| Manufacturer part number | 550-7500 |
| UPC | 806105486097 |
| Type | Filter locknut assembly |
| Includes | Locknut and threaded retainer ring |
| Top inside diameter | 15-11/16" |
| Bottom inside diameter | 16-7/8" |
| Part type | Pool filter part |
| Fits | Waterway Clearwater II cartridge filter |
| Shipping weight | 10 lb |
| Ships | Parcel |
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Questions and answers
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