Dustydog said:
Also worth placing the aquaroll off the ground, wood etc for further insulation
The ground often retains more heat than the air above it, so if it's not frosty during the day, then leaving the water container on the ground may allow it to keep a little warmer by drawing heat from the ground.
If the ground is all ready frosty, then the water container should be insulated from the ground, but not exposed to the air