Hi all, happy New Year! New member here with the question. I own a home with the pool and today when I was winterizing it, during spa drain, I noticed tiny air bubles coming out of one spot where sitting surface curls to a vertical line. The bubbles were tiny (1mm) coming out every other second. I marked the spot when spa was drained and it seems it was missing couple of the little rocks, which I understand the part of the cement liner. What kind of problem is it (if it's a problem at all) and how to fix it? Thanks!