Pool leaking - Who to contact

My 2 month old owner/builder pool has a leak. I believe it is at the skimmer. When I turn off auto-fill the water level rapidly drops to the bottom of the skimmer, but no further.

Since this is an owner/builder pool I do not have a pool company to call. Should I call the pebble tec guys, the plumbers, or a leak detection company?

Plug the holes in the skimmer with PVC threaded plugs or gizmos, then add water and see if it still drops. This will tell you if it is in the plumbing.