Ok so I have heard some say that under tank heaters are unsafe. I use them for both of my horned frogs who love to burrow right ontop of them. I'm not sure if this is because they enjoy the heat or due to the heater being directly under the "hide". I have heard of some instances of amphibians and reptiles preferring to cook rather than be in the open and vulnerable. So in the end what I am asking is are under tank heaters safe? When used as direct with corner inserts raising the terrarium up.