Not sure if it’s a leak or evaporation? There’s an easy test:
1. Place an empty bucket on one of the steps of your pool, in the water but not completely submerged.
2. Fill the bucket with water so that the water level inside the bucket and outside the bucket are the same.
3. Mark the water level on the bucket with a piece of duct tape or wax pen.
4. Wait at least 24-48 hours for evaporation to occur. If the water levels are still the same after 24-48 hours then your pool is fine! If your pool has lost significantly more water than the bucket, you may have a leak.