Problems with your pool liner are generally caused by a leak or a misaligned liner bead that, if left unattended, could cause considerable damage. Repairing a damaged liner is easy if you know how. Following are some simple steps most do-it-yourselfers can follow to fix a pool liner. For More Above Ground Pools
Look for the source of the leak and repair tiny holes with a vinyl liner patch kit. You'll need a "wet" patch kit if the leak is located under the water.
Use a coin to Indicate any possible leak sites. Remember that you can substitute food coloring or an expired bottle of pH reagent for store-bought dye. Turn the pool filter off for 60 minutes and squirt dye next to your marker. If the dye is drawn to it, you have located the source of the leak.
Make a temporary patch by covering the leak with patch material, heavy plastic or a piece of inner-tube. The water pressure will keep it secure.
Create a deep gully, drain the water from your pool, lift up the liner and pour dry sand through a funnel. Fill any empty spaces if escaping water has formed a deep gully. Using material from a repair kit, cut a round patch double the size of the tear, then thoroughly coat the patch with cement. If you're repairing an underwater leak, keep the cement dry by folding the patch in half. Quickly replace the temporary patch with a permanent one and smooth out any air bubbles.
Apply heat with a heat gun or blow dryer to stretch and lock your liner back in to its track. Another technique for realigning your bead is to apply boiling water. If the problem persists, consider a liner lock. You also may want to seek professional advice.
Reset your liner and use a vacuum to eliminate any air between the liner and the walls and floor. Remove the vacuum after the water has reached a specific location on the wall and allow the pool to refill. This guarantees a correct fit and will reduce wrinkles in your liner.
Consider replacing your vinyl liner if it is old and has been repaired several times.