o ring for prizm pro skimmer

[mollymonticello]

I couldn't figure out why the pump was leaking, so I took it apart, and I thought, "shouldn't there be an o-ring there?" I looked at the parts list on redseafish.com, and I am missing an o-ring. But they don't sell them.

I can't seem to find one online. Does anyone know where I can find an o-ring for my prizm pro skimmer? I need the one that goes inside the pump.

Thanks