How do you determine if you have a leak in a gunite pool?

Place a bucket of water next to the pool and use it as a constant. The bucket will lose and gain water due to evaporation and rainfall at the same rate as the pool. Mark the water level in the bucket and in the pool and watch it over several days. Be sure not to backwash or splash water from the pool during the test, and turn off the auto-fill if your pool has one. If the water level in both drops at the same rate, you do not have a leak. If the pool loses 1 inch and the bucket loses 1/4 inch over the same timeframe, you would have 1/4 inch of evaporation and 3/4 inch of water loss due to other conditions, such as a leak.