greenhouse

I'm in the process of building a greenhouse (unheated) and I plan to put a ~100 gallon stock tank in it to help moderate the greenhouse temperatures (thermal mass). I hope and think that it will not freeze (or maybe just freeze over the top) but I don't know that. Also, even with vents open...

This idea was a idea I found a while back First dig about 3 to 4 feet down to make the general shape of the greenhouse,next use the soil u dugout to make walls/hills on the outside edges,next add the green house film over the area,u can make it so it also collects water for your pond(make sure...