Scsims,

It's true this doesn't always work but many times if the the leak is not substantial it may work. It worked for me in a small holding pond once.

Not sure what to tell you on how much to use. It's pretty much trial and error. If it was me I would be willing to spend up to $500.00 worth to give it a shot but that's just me.

I would dump in on the inside of your damn of course if you're sure it's the damn that is doing it.

As far as your other question it's possible you leak will subside as many ponds seep a little at first. As organic matter builds up that should slow the seepage. Still if it was me I would try the bentonite "sprinkle method."

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.