Thank you to all who assisted.

On Saturday, equiped with SCUBA gear and dye, I proceded to the Hydostatic valve. It was working perfectly normally, no leaks, or any problems. From there, I went around the pool and eventually found a very small seperation (gap) on one of the plugged return pipes. I checked this previously, but the leak was tucked underneath and could not be seen without the SCUBA and dye approach.

I found some "Aquamend" epoxy, which set up and cured nicely.

Now, the leak is no more and the pool is in great shape.

Execpt -- the temp is VERY warm - thanks to very hot outside.

Thanks again.

john