Spa Pump Seals, Gaskets and O-rings
Spa pumps and hot tub pumps are both vacuum and pressure at the same time, and since they aren't supposed to leak, the various spa pump components are sealed together with the use of seals, gaskets and o-rings. Shaft seals are used to prevent leaking along the shaft seal, which results in leaking directly below where the motor meets the wet end. Volute o-rings, diffuser gaskets and pump union o-rings are the other most common parts replaced on spa and hot tub pumps.
Use a Teflon based lubricant on spa pump gaskets and o-rings. Shaft seals are not lubricated. Note that shaft seals do not touch the shaft, as the rotation speed of 3400 RPM would quickly destroy it. Pump shaft seals are joined only at the two seal faces, allowing the motor shaft to safely turn within. Replacing a Shaft Seal.