Garage tank question

[dabandit]

Ok here goes a stupid question. I have an un heated garage,it gets as cold as outside and heating it is not an option. Do you think a buttload of tank heaters would keep a 300g tank in the liveable range? Keep in mind last night it was -6 in there.
I would assume the answer would be no but I figured I'd ask because alot of people do keep tanks in the garage. It will be lit by 3 250w halides 6'' above tank by the way