I've used an aquarium heater on a plastic tote before, but I was only trying to warm from about 60F ambient air temp to 65F. Note that using just the aquarium heater, didn't warm up the entire bath. You need some motion to the water or you will only be heating the water right around the heater. I used a stir plate attached to the outside of my tote and the stir bar in the tote underwater to get the motion that kept the entire bath constant.
Here's a picture of my setup (it's pretty ghetto, but it worked - once I added in the stir plate). Note that I also added bricks to the one on the left lower the amount of water needed. Next time I will add in some bleach as the water got kind of nasty after a week like that.