QUOTE(lantern567 @ Apr 2 2008, 11:57 AM)

Philly Bill - I checked out your blog - that will be interesting to follow in the coming months! Seems like you are south of me, but possibly in the same hardiness zone. It looks like your pond is raised up above the level of the earth, which I would think would contribute to more severe freezing problems - something I'm worried about. Are you using the solar cover? Does a solar cover allow the pond to "breathe"?
The first pond is in the earth, up against a neighbor's house, and on a south facing wall, so I had very little freezing problem last winter - just a light layer one time, no danger at all to the fish with the Thermopond to keep it ventilated. Although we are just one half zone different from eastern Massacusetts (6b vs 6a) and one full zone from western Mass (5), this past winter was mild for us and severe for you.
The new pond is above ground and partially shaded but deeper at 26". I plan to wrap the tank in insulating material - bubblewrap with reflective coating available from home supply stores - and then build a masonry surround.
I never had to use the solar cover last winter. It has one side with the bubbly texture that should allow for gas exchange. I have seen posts from people that cover their ponds entirely with it. If I use it on my new tank next year, I will be rather safe than sorry and not cover the entire tank, leaving space for the waterfall and floating heater.
Apparently the solar cover not only heats the pond, but is great for predator control. Herons hunt by sight, and raccoons like water, so the plastic effectively hides the pond from them. I also hear fewer leaves get though it than with a net.