We purchased our home seven years ago with a small concrete koi pond in the front yard. The problem is they really on only did it half way. It was so murky that when I cleaned it out I discovered several Koi in it already. I have been trying to keep it up for several years now and I have thinned out the fish (with the help of a herron). The proble is that its just too shallow for one. I have put in the right pumps filters (UV included) but its just too shallow. My question is, can I make it deeper without tearing it out and starting over? If I have to tear it out It is not going to be a pond anymore. Can anyone help me with this? These are some old pics but it has not changed much except for the plants and a herron decoy.