I am considering all that,Pat. Thinking about doing a lean-to half high tunnel on one side or all three tanks and insulating the back and tops of the tanks. I can get a 300-400 square foot floor area out of that to practice keeping stable, until I find out the best way to go larger.
30F this morning and the water in the completely exposed tanks is 58 degrees. I bet it would be well into the 60’s with the north sides and tops insulated. I think I need to understand the approximate night time rate of flow of heat from that tank per square inch of surface.