Good luck with your project and enjoy your new pond.
I use above ground galvanized livestock tanks for all my ponding. Some of them have holes in the bottoms and I use kiddie pools for liners. I always drain my 90 gal poly tank each fall because I'm afraid the drain will freeze and crack.

I am in zone 6 and we have had COLD temps the last couple of days. Highs were 8*F with wind chills of -15* to -25*.
My round 160 gal tank had about 5" ice on the top yesterday. I have an airstone and a pump at 1 ft. It just has some babies from last summer that I'm not too worried about. I will need to get out the heater today to melt a hole in the ice. We are suppose to hit about 25* today.

In your zone you might think about using a heater all winter.

Hey that sounds like something I would like to do!!! I have a patio(concrete), that I was gonna do a raised pond on, using those cement building blocks, but someone mentioned if I knew the load bearing of the patio, cuz it could crack with all that weight, but just a stock tank sounds good to me, I may get to reconcider this project after all! This is a pic of my idea that I was concidering....

Here is a link that might be useful: {{gwi:184092}}

Just remember that water weight approx 8 pounds a gallon and say a 500 gallon tank would weigh approx 4000 lbs. That weight would be distributed over the area of the tank though. You might think of placing it just to the edge of the patio. I have seen them surrounded with the stones also and I think it would have some insulation factor.

Be sure and plan on using a heater if really bad weather. My 160 gallon tank had 10" of ice when I got out to it and the air stone and pump had both froze in and shut down. I lost some babies because they had no air.

OOPS...I didn't look at the pic first. That cement looks pretty thick. Ask a cement guy if it should hold up to the weight. Obviously you can't put it on that slope.

That looks good to me!

Thanks guys! Calamity, that's exactly what I want to do. Had originally planned the pond beside the garage digging down a foot so that part of the pond would be underground and insulated then raise the walls 2' above that, but it would not get 6 hours of sun a day, limiting my plants. So I decided to use a stock tank and move it to the patio/driveway and keep it 2' deep for the sun. I have a perfect place for it. Can't imagine with the weight distributed over the stock tank, it would crack the cement. Since I would drystack the retaining wall stones, it would be totally portable! I will use a capstone on the top to hidw the liner lip. Will either keep a pump running all winter or use a stocktank heater to keep a hole in the ice
I had a little fountain pond for years made from 2x12's with a liner on top of a gravel base. I kept a pump running all winter and it never froze solid and I kept goldies in it year round and they were fine year after year.
What kind of paving block did you use, Calamity, that allowed you to round the corners? Looks great!

My pond is a stock too. I put it inside a rectangle form of landscape timbers and put styrofoam between pond and wood to insulate. Have flat rocks around edge of pond to disguise edge and sit pots of flowers around the edge in summer. Forgot to mention it is inside a -- hmm-- how to describe it. I have a deck with a ramp going down one level then turning back to the right and makes a "U" shape and that's where I put my pond. Long winded, I know.