Bump for cheezy.

That's a great question, but I have no idea what the answer is. I wouldn't think the clumping of suspended clay particles, on its own, would be enough to stop a leak. How big is your pond? Could you tell how big an area had leaking water before?

More knowledgeable folks should be able to provide a better answer soon.

"Only after sorrow's hand has bowed your head will life become truly real to you; then you will acquire the noble spirituality which intensifies the reality of life. I go to an all-powerful God. Beyond that I have no knowledge--no fear--only faith."