Patching Pool Liner. Put your scuba gear on, take a bottle of coloring in with you. Look at the liner real close, if you see something that looks like a hole, squirt some food coloring in it. If it goes in, you got a hole, start patching pool liner.

Swimming Pool Liners
1. Patch rips in a vinyl liner with an inexpensive repair kit from any pool dealership. Just apply the waterproof bonding agent to the vinyl patch material and place it directly over the rip - even underwater. Smooth any air or water bubbles out from under the patch.

2. Replace the liner if the damage is bad enough - this will be less costly than a paint job or a fiberglass replacement.

Above tips and more about patching pool liners can be found at eHow.com, their link can be found on the right of the page along with a couple of other links.

Patching Pool Liner Problems
A leak in a pool liner must be stopped immediately or it will get much worse. Sand will be washed out from the leak and the liner pushed into the gully, which will further stretch and weaken the liner. If the liner then tears, vast amounts of sand will suddenly be washed away, possibly weakening the pool framework to the point of the collapse. If such a leak develops, get out of the pool quickly and evacuate the area.

Wear goggles to look for the leak. Washed out sand may wrinkle or depress liner. Dirt released at pool bottom will be drawn to a leak. Place a piece of patch material, inner tube, or heavy plastic over the leak immediately. Water pressure will hold it in place.

If escaping water has created a deep gully, drain the pool, raise the liner, and pour dry sand through a funnel to fill the void. Cut a patch from material supplied in the patching pool liner kit, and coat with cement. Patch should be circular and twice the size of the tear. Spread cement over entire surface of patch. If tear is under water, fold the patch in half to keep the cement as dry as possible. Working quickly, remove temporary patch. Open adhesive coated patch immediately and apply. Smooth out any air bubbles.

To help prevent leaks and patching pool liners in the future, observe these simple rules: Use only plastic plates, cups, and utensils in and around the pool, forbid children to play with sharp toys or BB guns in the vicinity of the pool and see that swimmer's toenails are trimmed to a reasonable length. Keep a patching pool liner kit and extra patching material handy. Even when it's too cold to use cement below 45 degrees, water pressure will usually hold a temporary patch in place. Be sure to know what your children are taking in the pool. This way you can avoid future liner holes.