Waterway Weir Foam, Spa Skimmer, 865-1000

The Waterway 865-1000 is the weir foam for a spa skimmer. It is the block of closed foam that sits inside the weir door and gives it the buoyancy to ride on the water line.

Why a flat weir stops skimming

The weir door is what concentrates the flow at the surface, so the skimmer skims a thin layer of water instead of drawing from deeper in the spa. That only works while the door floats. Once the foam waterlogs or compresses, the door drops, the surface film stays where it is, and the skimmer can start pulling air.

What you are buying

The foam on its own, measured at 5.5″ x 2.35″ x .85″. Compare it to the piece you take out before fitting, and if the door itself is cracked or the hinge tabs have broken, the door is a separate part.