Pond Boss Forums POND CONSTRUCTION Soil questions Pond holding water...success notes

Here is my story.
My pond was built 2005. First year had only a puddle of water in it. The second year it had somewhat bigger puddle. It would go up about a foot after heavy rain and drop a foot in a day or two. I bought 14 tons of bentonite and hired a guy with bulldozer to apply it. He spread it with fertilizer spreader all over the pond surface (except the puddle), mixed it in with a disk and covered it with about 1 to 1.5 ft of clay. Then I bought 150 gal of ESS-13 and poured it into the pond in hope to stop the remaining leakage.
The pond held more water (about 3/4 full) but was still leaking 1 to 1.5 inch/day depending on water level. I also realized that the watershed of my pond was marginal about 6 to 1 as opposed recommended ratio for our area between 10 and 20 to 1. Therefore about three weeks ago I dug about 800ft of trench crossing the adjacent slope bringing in water from another 7 ac making the total watershed about 11 ac. Since then we got more than 6" of rain and the pond is first time, though still leaking, completely full.
The general area my place is located has excellent materials for pond building. All my neighbors have non-leaking ponds. In fact I had to spend extra money for special septic due to non-permeable soil. As the bad luck has it the ravine I used as base for the pond had at least 20 ft of sand several feet under the surface clay. While the contractor was building the dam they dug themselves trough the clay to the sand and caused all the trouble. The guy used several tons of bentonite to cover the sand and placed several ft of clay on the top but year later I found a hole covered only thin layer of clay in one side of the pond. The good thing was that I ended up with a pond about double the surface area than originally planned because to complete the dam they had to get material from the side of the ravine making the pond about 0.7 ac.
I will make few more attempts to find the leak but at this point it is mostly wait and see how it will behave and hope that it will get better with time.
If it will still leak unacceptably I will try traditional way used in fish farms at the area I grew up at. Cows or horse manure. It supposedly promotes growth of bacteria that looks like slime sealing the seepage. Perhaps even clean biomass such as grass or straw could work too. I am thinking about spreading it in the winter on frozen pond and let it sink at spring.