We have noticed a leak for about the past wk and have been getting help here to locate it. We were hoping it was on the plumbing side. My husband was home today and we were capping off the returns and such to rule out the shell when I noticed a hole at one of the returns. Will attempt to post picture. It is on the bottom of the return. This particular return is to be used for the heated water if using the solar system but we have opted out because of all the necessary hoses we were concerned about leakage! We had air in our system earlier this week from a cracked lid on the skimmer at the pump, but the bubbles were gone after we replaced it. Could this have been caused by pressure blow out from the cracked lid, as I have read in other posts? We were considering making the opening larger for a light, that way we wouldn't have to patch, and have a light also. While attempting to take a pic, I noticed what appeared to be scratches at the "working" return. When I rubbed them, the color/pattern just came off! I have read posts on liner damage due to chemical abuse. This would have been our 4th season with this liner. The 1st yr we filled and used wally world chemicals. Since then, BBB. I am careful to pour of a few minutes. Will attempt to post pics. Any help will be appreciated. Thanks!