Heating an entire room with a space heater is not the most economical or ecological solution. The tank will be fine going down to even 60 degrees at night. Allowing it to warm during the day with an undertank heater. To prevent heat loss you can also put aluminum foil (shiny side in) behind the background picture on the outside of the tank (if you have one). Additionally you could insulate 3 to 5 of the sides with pink/blue insulation foam board.
Heating pads work well, just need to have one that puts out enough heat to warm the tank faster than it is cooling and within 2 hours of being put on.
New York, NY