posted 9 years ago
What sort and size of tanks?
We don't get as cold as you do, but there's a ~15x20ftx4.5ft cement reservoir on my parents land, presumed built by the previous owners who homesteaded on the property from shortly after WWII; more than 35 years old at least, possibly more like 60.
While it's rare lately, 15-20 years ago hard freezes were common; we could skate on the ponds as often as not. This reservoir is 3/4 above ground, and ices over freezes an inch or two thick for a while even in recent mild winters. It still holds water just fine.
A greenhouse would definitely help prevent freezing, though how much would depend on the details of both greenhouse and climate; I don't think the barrel of water in my tiny unheated greenhouse froze last winter, but if it did no harm was done and I didn't even notice.
'Theoretically this level of creeping Orwellian dynamics should ramp up our awareness, but what happens instead is that each alert becomes less and less effective because we're incredibly stupid.' - Jerry Holkins