Sta-Rite Pump Diffuser — SW5P4R (RC1271PSS)

Genuine Sta-Rite / Pentair diffuser for the SW5P4R pool pump. The diffuser sits over the impeller and channels the outgoing water into the volute — it’s the second-most-important hydraulic surface in the pump after the impeller itself, and a worn diffuser is the usual culprit when a pump primes slowly or loses head pressure at the returns.

Five-vane design with an integrated copper wear ring — the copper ring is the sacrificial surface that runs against the impeller shroud and takes the hydraulic hammering that would otherwise chew out the diffuser body itself. When the copper is scored or bluened, swap the diffuser before the wear reaches the plastic housing.

Installation notes: replace the diffuser o-ring at the same time — it’s a cheap part but a hardened o-ring will leak against a new diffuser and cost you the whole prime. Also inspect the impeller wear ring for matching wear; diffusers and impellers wear as a matched pair and swapping one against a worn other undoes half the improvement.