I'm not familiar with acrylic at all, but I'm using a zoo-med under tank heater on the bottom side of a heave duty roughneck rubbermaid to house a colony of dubias. The bin is made from polyethylene plastic, heating point is very high so I'm not concerned with the temperature getting to 105-110F, but I have a rheostat just in case. Everyone uses them for all their advantages, although I wouldn't recommend using one on your acrylic. I agree with George that it could potentially let out toxic fumes harming your amphibian. The heat pads all have that warning sign, but I've never heard of stories where Rubbermaids or Sterilites have caught on fire or melted from them.