How do you find holes in pool liners?

Use a needless syringe and fill with a dark food coloring, release over area of suspected leak. If there is a hole in liner, the food coloring will disappear through the leak, otherwise it will float away. In a deeper area you will need equipment to go under the water. Once the leak is detected, use underwater patch material found at pool supply company. Cut patch about two inches larger than hole in liner and center over hole, smooth patch flat.