Sta-Rite C21-2 Diffuser Ring
This is the C21-2 diffuser ring for Sta-Rite Dyna-Glas/Dyna-Max Series in-ground pool and spa pumps. Because it channels every gallon the impeller moves, a cracked or worn diffuser ring shows up as reduced pressure, an external leak at the pump body, or a rattling noise even when the impeller itself is in good shape.
A worn or cracked diffuser ring lets water recirculate internally instead of moving out through the discharge, which shows up as a pump that runs but delivers noticeably less pressure than it used to. Replacing it along with the impeller during a rebuild is common practice, since both parts see the same wear conditions.
Key Features
- Genuine-fit Sta-Rite C21-2 replacement diffuser ring
- Built for Sta-Rite Dyna-Glas/Dyna-Max Series in-ground pool and spa pumps
- Directs impeller output into a smooth, pressurized flow toward the discharge
- Direct fit replacement for the original Sta-Rite part
Applications
- Restoring lost pressure on a Sta-Rite pump with a cracked or worn diffuser ring
- Rebuilding Sta-Rite Dyna-Glas/Dyna-Max Series in-ground pool and spa pumps
- Routine wear-part replacement during a pump rebuild alongside the impeller and seal
- Fixing an internal leak or recirculation loss inside the pump body
Specifications
- Brand: Sta-Rite
- Manufacturer Part Number: C21-2
- Part Type: Diffuser ring
- Fits: Sta-Rite Dyna-Glas/Dyna-Max Series in-ground pool and spa pumps
- Quantity Per Pump: 1
- Condition: New
Frequently Asked Questions
Q: What causes a diffuser ring to crack?
Age, thermal cycling, running the pump dry, and years of sand or grit passing through the water all contribute. A sudden crack after a hard freeze is also common on pumps left full of water in cold weather.
Q: Can a cracked diffuser ring be glued or patched?
No. A cracked diffuser ring should be replaced rather than repaired, since a patch will not hold up to the pressure and vibration inside a running pump.
Q: How do I know if my diffuser ring needs replacing?
Reduced pressure or flow with the motor and impeller both in good condition is the main sign, along with visible cracks, chips, or wear where it seats against the pump body.
Q: Should I replace the impeller at the same time?
Inspect it while the pump is open. The diffuser ring and impeller wear under the same conditions, so it is common to replace both during one rebuild rather than opening the pump twice.
Not sure this is the right part? Send us a Picture of the Pump Plate on your pump and the CLR Marine team will confirm the correct diffuser ring.
CLRMarine
