i have a vivarium that measures 30" x 12" x 12" and i am wanting to put a leopard gecko in it, i know that the temperature has to be 90 degrees in the warm end but at the moment i can only get it to 80 degrees. i am using an exo terra medium desert heat mat with a habistat matstat, the substrate is 2 layers of kitchen roll. if anyone has any suggestions of how to get the temperature up they would be much apreciated. thanx