Pentair Index Plate O-Ring, 35505-1246

This is the Pentair 35505-1246 o-ring for the index plate inside a Sta-Rite WC212-134 plastic push pull filter valve. It is the genuine part, not a hardware store ring picked for a close size.

What goes wrong

The index plate ring spends its life squeezed between two surfaces with pool water on one side of it. Over the seasons the rubber takes a set, loses its spring and then hardens, and the seal that used to be tight starts letting water slip past the plate. The symptoms are usually water going where you did not send it, or a valve that never feels quite sealed no matter how it is set.

Fit

Our record lists it for the Sta-Rite WC212-134 plastic push pull valve and notes it may fit other valve models. Because it is sold by part number and not by measurement, compare it against the ring you pull out before you rebuild the valve.

Replace rubber whenever the valve is open. A ring that looks acceptable but is already several years old will usually be the reason you are back in the same valve next season.