Hayward Bulkhead O-Ring (After 1996), SX360Z1

The Hayward SX360Z1 is the bulkhead o-ring for Hayward filters built after 1996. It is the genuine Hayward part, and it is also listed as 20-SX360Z1 and, on DE filters, as the diffuser o-ring or union o-ring.

Size

Outside diameter 3-1/8 in., inside diameter 2-3/4 in., thickness 3/16 in. Measure the old ring if you are unsure; a ring that has taken a set will read a little larger and thinner than these figures.

Which filters

Pro Series side mount sand filters S210S, S220S, S244S, S310S and S360S; Pro Series Plus S311SX, S311SXV and S360SX; MicroClear vertical grid DE filters DE2400, DE3600, DE4800 and DE6000; and Super StarClear cartridge filters C2000, C3000, C4000, C4500, C5000 and C5500.

What it does

An o-ring is a simple circular gasket that seals two parts against each other. Here it seals the bulkhead fitting to the tank. When it ages it hardens and flattens, and the connection starts to weep. A new ring is the fix, and the bulkhead fitting and spacer are separate parts if those turn out to be the problem instead.