I have a pond feature in my yard that has developed a leak in the liner. I have patched the leaks I could find and then painted the liner with "Flex Seal" It worked fine for a while, but is now leaking again. When I removed the rocks and examined the liner, the Flex Seal had blistered up and will just pull away from the liner as in the attached pictures. I almost have to use a liquid product similar to Flex Seal to rebuild the liner. Can you suggest something to make the Flex Seal bond to the liner? I called Flex Seal and they just said to use 2 or 3 coats. That doesn't seem to offer much hope of a bond.

 

I have a pool cover that I patch. Nothing seems to stay very well attached to that either. Flex Seal peeled of that too.

Based on the age of the liner it may be time for a replacement.

 

Unless you can thoroughly clean the patch area nothing will stick very well. I would just replace the liner or leave it in place and install a new liner on top of it.