Pond Supply

I know I have asked questions about this before but I have revised my questions a bit. My cousin and I are planning on building a fish pond at his farm as we love to fish. We got the space, we got the tools, we got the approval. We’ve changed the dimensions to 25 ft. long, 10 ft. wide, and about 4 ft. deep as it gets cold here in South Dakota and don’t want the pond to turn into solid ice.

We plan on buying a pump, possibly a skimmer, and some "good" algae for the pond. One thing we were wondering is if it would be ok to use a roof liner as the pond liner. The ground is pretty porous around here and the liner has been outside for about 3 years so you would think that the chemicals would be washed off of it. If there’s no possible way that would work, we would be willing to buy a pond liner.

So does the overall idea sound good? I’ve drawn out the blueprints and written down everything we are going to need. We have also researched just about every website for pond building. Thanks and God bless!