It was a big lesson learned for me. I have a five feet deep koi pond. It was rebuilt about five years ago with Firestone 45 mil Pondgard liner. Two months ago, the water level kept dropping, 5 inch a day. I looked ant every pipe and system and found nothing wrong. Two weeks ago, I decided to have a contractor to do the pressure test. Every single pipe was in a good condition, no leaks. The contractor drained the pond and checked the bottom drains and air pipes. They were good. We filled the pond. The leak got much worse, over one foot dropped within 24 hrs. We drained the pond again and checked the liner carefully. We found lot of tiny grooves on the line. Absolutely they looked like someone scratched the liner with a very sharp knife. Many grooves became a small holes. We thought the koi ate the liner. We all know Koi’s teeth are very behind the mouth. Guess what, I remember that there was a box turtle in the pond two years ago. Since my pond is very steep and deep. The turtle couldn’t get out the point. It must struggle in the pond for a long time and tried to get out. Other than the turtle, I can’t think of any other reasons. I have the koi pond for over 20 years. This was the first time for me and my contractor to see such a thing. Now, I have to rebuild it again. Turtle can damages your liner!
