My neighbor has gone through two incidents of leaks in his liner. The first time, he could never find it; had to replace the entire liner.

He had the same issue this summer - losing several inches of water every day. He hired a pool leak service provider. I don't know the specifics, but something similiar to the following equipment was used:

http://www.leaktools.com/mm5/merchan...egory_Code=VLD

My understanding is that a continuous connection to ground is established where ever there is a hole and the operator can hear it and zero in on the leak through sound and headphones. In my neighbor's case, there were about 8 different holes; the operator also found a couple that were real close.

I believe that my neighbor paid $200 to $300 for the locating of and patching of the leaks - a lot better alternative than replacing the liner.

You might check into this in your area.