The following test will allow you to confirm whether your water loss in your pool is attributable to normal evaporation or a leak. In order to have enough volume for the test, you will need a five-gallon bucket, one of those big white or orange buckets like they have at your home improvement store. A description of the test follows:

• Fill the pool to the normal operating level (half way up skimmer opening) – turn off the autofill if there is one.
• Fill the five-gallon bucket with pool water.
• Set the bucket with the pool water in it on the 2nd or 3rd step of the pool, the step selection should allow just a little bit of the bucket to be above the water.
• Get the water level in the bucket and the water level in the pool at the exact same level (i.e. the water inside the bucket is touching the bucket at the same place as the water is touching on the outside of the bucket). Sometimes you have to put a brick or rock inside to keep from tipping over or floating away.
• Mark the bucket with a marker to know where you started.

The above test will create a control environment whereby the water inside the bucket is exposed to the same environmental conditions as the water outside the bucket: (1) The water in the bucket is immersed in the pool, so it's the same temperature. (2) There will be comparable airflow across the water inside the bucket as in the pool. (3) The water inside the bucket is the same chemical composition as the water outside the bucket.