one benefit of using a plastic tub that is 6-8 inches tall, is that it has alot less airspace to heat. the overall volume of air is less so you could use less heat/wattage compared to a tank. if you are set on a glass tank, that's fine, you just need to find the right heat source and wattage to overcome the heat loss you will have in a colder room. che's and bulbs and heat pads can all work it set up properly and you have enough wattage for the job. i also suggest a thermostat to control any heat source.
vaughn