Well tadpole here is the latest in my expansion plans, I should say my wifes' plans, where I will be putting in a second pond will actually be lower than where the pond is now, so she thinks it will be just the same as when I did the stream into the pond, and in some way she is right. From the pond edge to where she wants to expand is about 8" lower so I think I can dig it down to the required 4' and have a bit of a waterfall from one pond to the other.
I think I will also put in a second skimmer and plumb it to the weir at the top. I think that the pump on the original pond can be used in the new pond and put a smaller, 5000 gph, in it's place.
Since it is now getting colder, I have purchased a small pond heater to keep the fish that she so lovingly fed all summer, alive.
I will be posting many more questions next spring I'm sure.
Thanks to all for their advice/comments