I recently had an in ground vinyl liner steel wall pool put in a few years ago. The builder used portland cement for the bottom. He told us it was better than the vermiculate that other builders use. Within two seasons the pool floor began to develop depressions. The cement bottom was giving way. The builder came back removed the liner and patched the cement floor. When he put the liner back in he found several pin holes in the liner and stated he had to put a new one in. He advised that the pin holes were caused by unbalance water and the fact that I didn't buy the chemicals from him. Now i'm finishing up the fourth season with the new liner and have had to patch 9 holes on the floor this season. It seems every week I have a new hole.
My question is is this normal for a liner this old? Could it be caused by a chemical problem? Is it a result of the cement floor the builder used (the floor is very bumpy)?
Also the holes are only in the three foot shallow end, the liner color seems extremely faded already when I compare it to a new piece I have. And if it matters the shallow end is in direct sunlight all day.
Thanks for your help