With a mask and snorkel submerge yourself underwater and look clearly for any signs of tears or cracks. Check seams around skimmers, valves and plastic connections, as these tend to weaken and crack with chlorine, chemicals, sunlight and UV. A good way to tell if it's your skimmer is if the water level doesn't drop below the line of the skimmer. One way to determine the level or height of the leak is to allow the water level to drop until it stops - then you know you have reached the height of the leak. Of course if the leak is on the bottom of the pool you can loose all your water!

Once you think you've found the leak, take a dye (food coloring works well) and squeeze it gently near the suspected area under water. Ff it gets visibly sucked into the tear/crack, you've located a problem spot.

Use an underwater patch kit, then refill the pool and keep your fingers crossed. If you want to hire a professional for stubborn leaks FIND A POOL LEAK AND REPAIR COMPANY NOW»