Pentair Challenger Diffuser, 3/4 HP Full Rated to 1-1/2 HP Up Rated, High Pressure, 355188

The Pentair 355188 is the diffuser for Challenger high pressure pool pumps in the 3/4 HP full rated through 1-1/2 HP up rated range. It is the genuine Pentair part, the same one fitted at the factory.

What the diffuser does

The diffuser sits over the impeller and turns the water the impeller throws outward into usable pressure on its way into the volute. It is a close tolerance fit, and when the opening around the impeller wears or the body cracks, water simply circles back inside the pump instead of going down the pipe. The symptom is a pump that runs and sounds normal while the returns weaken and filter pressure drops.

Getting the right one

Pentair builds the Challenger in high pressure and high flow versions and the diffusers are not interchangeable. This is the high pressure part. Check the horsepower and the build of your pump against the range above before ordering, and look at the impeller while you have the pump open, since the two wear as a pair. The hex head screw that retains the diffuser is a separate part if yours is stripped.