Hi, Rick,

That's what I thought, and, yes, suction side is, logically, everything from the impeller of the pump back to the skimmer. Pressure side is everything the other way...pump up to the filter, thru the multi-port valve, etc.

So that Sp 711 valve is not the issue nor is anything on the pressure side since a pressure side leak is water spewing (leaking) from the system.

Suction side leaks, like yours, are characterized by air being drawn into the system. Okay, you've got a suction side leak and there are no moving parts on the suction side. The most common leak is at the o-ring on the pump basket. I know you said you've got suction at that basket but check the o-ring carefully again. Make sure it is seated correctly and eliminate it as a possible source.

The next most likely would be the union between the suction side pipe and the pump basket. There is typically an o-ring there as well. Ensure that it is in place.

I'm still stumped, but it sounds like it is getting narrowed down. An underground suction leak is always thought of but that is very unlikely. That system is drawing air somewhere betweem the skimmer and the impeller on the pump....we'll (you'll) find it.