This is a "new" pool to me, so I have very little information on what happened before me. I replaced the sand in the filter tank, but nothing to the pump. I did some re-plumbing last year that sealed all of the leaks in the plumbing itself. As far as I know, this leak was not there last year. It looks like something should go in the square that water is leaking from, but I'm just not sure what.