I am thinking about building a small pond in my back yard, the problem is that there's no creeks, or spings running through, so I'd have to fill it up with rain water, or some other unknown way.  I fish a small pond that has what is basically a large filter, like in a fish tank, or an aireator.  Does anyone know where I could buy one, and the approximate price for one, that would be for a small pond app. 100ft x 100ft x 20ft deep?  Any other info concerning builing a pond would be greatly appreciated.  I live in SW Pa.

You might want to call your conservation Department or Game and fish department.  They usually have plenty of info for people wanting to build a pond.