
Quick overview
- Genuine Hayward The factory o-ring, part CX120D.
- Micro-Star cartridge filter Listed for use with the Hayward Micro-Star cartridge filter.
- Listed at 5-7/8 in. ID, 3/16 in. Check both figures against the ring you are taking out.
- Seals the lid This o-ring is what holds the filter lid watertight while the pump is running.
- Lubricate on assembly A silicone based o-ring lubricant helps it seat evenly and stops it pinching as the lid comes down.
- Replace rather than stretch An o-ring that has flattened or taken a set will not reseal, and tightening the lid harder damages the lid instead.
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Product details
The Hayward CX120D is the filter lid o-ring for the Micro-Star cartridge filter. It is listed at 5-7/8 in. ID, 3/16 in., and it is the seal between the lid and the filter body.
The part that stops the lid leaking
Everything above the o-ring is under pump pressure the whole time the system runs. When the ring is fresh it fills its groove and seals with very little clamping force. When it has flattened, cracked or taken a permanent set, it stops sealing, and no amount of extra clamping brings it back. Cranking the lid down to chase a drip is how lids get cracked.
Fitting it
Clean the groove and the sealing face before the new ring goes in, then give it a thin film of silicone based o-ring lubricant. That helps it seat evenly and keeps it from rolling or pinching as the lid comes down. Use silicone rather than a petroleum grease, which swells the rubber over time.
Before you order
Measure the old ring against the 5-7/8 in. ID and 3/16 in. figures listed here. Cartridge filters in the same range are not all built on the same o-ring, so the measurement settles it faster than the model name does.
| Brand | Hayward |
|---|---|
| Manufacturer part number | CX120D |
| UPC | 610377004138 |
| Type | Filter lid o-ring |
| Dimensions | 5-7/8 in. ID, 3/16 in. |
| Part type | Pool filter part |
| Fits | Hayward Micro-Star cartridge filter |
| Shipping weight | 0.06 lb |
| Ships | Parcel |
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