Heater question.

The floors of my house are being redone and there is asbestos in the old tile. I have to leave for about a month while they take care of that and my fish will be in a 30 gallon long instead of the normal 100. I have a 450watt Aquatop heater in the 100. I do not have a heater for the 30 long. Could i use the big aquatop heater? I think it would work but i don't know if it would cook my fish.

that's what it seems like but the temp is always spot on.