I had American Leak Detection out to my house this morning. I really like these guys. The local office has been great to work with over the past few weeks of me bugging them with questions and the technician that came out this morning was on-time, courteous, and thorough.
He spent about two hours checking everything on my pool. Overall, it's good news. None of the plumbing leaks at all and the pool is, for the most part, structurally sound. It does need new plaster, but we already knew that. He found a leak in the skimmer throat where the plastic is supposed to butt up to the plaster. There is a gap there about 1/16" wide and it's drawing water. He used a syringe with a florescent dye and showed me how the dye got sucked into the crack. He didn't measure the loss rate, but he said it was completely reasonable for that leak to drop the pool >1/2" a day. The fix is pretty simple as there is no digging and no cutting of concrete. I'm going to look into fixing it myself first, but he quoted me $450 for a permanent fix using "polymer grout" that gets injected in behind the skimmer's plastic. That seems a little steep, so I'm going to see what I can find about the process and product used. It shouldn't be that big of a deal. The other option he presented was to use pool putty epoxy and jam it into the crack, but he said there's no guarantee on that holding up and it is a temporary fix at best.
Hopefully, that is all that is wrong and we can be done with the heavy water usage and the loss of salt level (due to refilling with fresh water every day).
Does anyone know anything about the polymer grout? He says it's much like the expanding foam product "Great Stuff," but it doesn't get rigid when cured. It stays flexible so it can adapt to any earth movement, etc. He showed me how it is hollow beneath the area of the leak, so they'd drill a small hole in the plastic throat of the skimmer, squirt in the polymer grout, and then wait an hour for it to cure. Then, they'd clean off any that oozed out and finish it all off with some epoxy putty to make the plaster-to-plastic transition look nice. He says that last step is completely optional as it doesn't do anything for the leak. It's just cosmetic.