The wet end of your spa pump is the part that gets wet, or through which water flows. Most spa pumps don't have a strainer basket, so the wet end is composed of the Volute (impeller housing), the Impeller and the shaft seal. The wet end is attached to your spa pump motor by means of bolts attaching the motor to the back of the volute, and the motor shaft is threaded onto the impeller.
Spa Pump Wet End Leaking: If you find a puddle of water under your spa pump, it most likely is the shaft seal, or it can be a loose union, or misaligned union o-ring. If leaking from the seal, you can often visually see the water dripping out below where the motor shaft passes into the wet end. If leaking from the wet end discharge or outlet port, you'll see water running down from the discharge area. Volutes don't normally develop leaks, but they can crack from freeze damage or other calamity. Wet ends can also leak on the Volute o-ring, aka seal plate o-ring, but usually only if you have recently opened up the wet end, and just didn't get it closed tightly, or sealed properly with the Volute o-ring.1-1/2 inch V thread or 1-1/2 FVT