I had a 3" hole in my liner about 6 years ago. I drained the water below it, cleaned and dried the liner, fitted the pieces together as best as possible. I went to the aquarium store and bought aquarium sealant that is put around the inside of the aquarium to make sure glass is completely sealed. The hole stayed sealed up for 3 years until I replaced my liner.Oh man. This is making me wonder if I need the concrete cloth. Arrrggghhh. Sorry that happened!