As they say, "if it wasn't for bad luck, you'd have no luck atall!"

With an AG pool, the obvious first step is to go over the outside of the pool carefully. Once you've eliminate the bits you can see, all that's left is the floor!

Unfortunately, that's harder. You almost have to have SCUBA: the process of diving down stirs the water so much that you can't follow the dye currents. Here's a video of me leak checking a skimmer throat (pump off, of course): https://www.youtube.com/watch?v=Y90c7pYMgPc