Sta-Rite 21 in. Filter Tank O-Ring, System 3

The Sta-Rite 24850-0008Z is the tank o-ring for System 3 filters with the 21 in. tank. It is a Pentair part, and it fits the S7S50 and S8S70 sand filters among others in the System 3 family built on that tank.

Check your tank size first

System 3 filters come in more than one tank size. The 25 in. tank, used on the S8D110, takes a different o-ring. If you are not sure which you have, measure across the tank at the seam.

Fitting

Clean the groove, lightly lubricate the new ring with a silicone o-ring lubricant, seat it and bring the tank halves together evenly. A drip at the seam after reassembly usually means the ring was pinched or the groove was not clean.