Leaking pools that are constructed from concrete will leak from one of two basic areas. The structure or the pipes underground.
The first step to detect a leak is to determine if the leak is structure or pipes. Depending on how the pool is built will factor in how to isolate the two.
Once isolated to what area is leaking then the focus can be applied to the structure or the pipes to avoid unnecessary test of a system that does not appear to be leaking.
Every pool is like a fingerprint as to no two pools are built the same. Even cookie cutter pools side by side have slight differences.