[marktwain]

If the aquarium is inside, how could freezing temperatures cause a crack?

Lack of fossil fuels, and limitations on their use could have caused a reduction in heating of the building.

[DUMBGRUNT]

—”Lack of fossil fuels, and limitations on their use could have caused a reduction in heating of the building.”

Possible but not probable.

Water has a very high specific heat capacity close to that of gold, it is up there in its ability to carry heat.

With that volume of water, the change in the water temperature would be very slow, with not much thermal shock expansion/contraction in the system.

Now my new improved (cheap) Pyrex bowl did not like the transition from the refrigerator to the oven.
IT DONE BLOWED UP REAL GOOD!... A major manmade disaster.

Just stay with the old Pyrex and avoid the new stuff.