wednesday13
Thank you so much for your continuing, experience and knowledge based help. Very much appreciate it and grateful.
So what you are saying, I think, is that if there is a hard solid surface behind the rubber liner, a catfish spine can only penetrate the distance equal the rubber liner thickness, that is 45 mil, and this will leave only a pinhole, and pinholes don't leak. Is this what you are saying? Why wouldn't a pinhole weep water?
There are 5 layers of 6 mil greenhouse plastic film protecting our rubber liner all around from the outside elements - roots, rocks, sharp coral chips, sharp gravel, etc.. So that's another 30 mil of penetrable depth for a stab.
There is half a dozen vertical 4x4 posts inside the pond behind the liner with the liner wrapped around them by water pressure, and this is where there are narrow vertical places with the liner unsupported from behind. Where the posts meet a wall. IDK if this makes sense, hard to describe, easier to draw
EDIT:I also just remembered that I placed some styrofoam in the two bottom back corners to fill them up a bit and smooth out the corners a bit. These would be the weak spots too.
So if you'd only were concerned about these narrow vertical portions of the liner, they perhaps could be protected far easier than all of the liner, but not by cow matts, which in your picture were laying flat on the bottom, I assume.
There are also folds and wrinkles in the liner, from a few inches up to a foot wide, many run for 20-50 ft distance. Would this concern you (in the case where you solved all other problems and left the rest of the main liner unprotected)?