The heat mat on one of my tanks decided to stop working. I thought it was the rheostat but that's working just fine. I won't be able to get a new one for a day or two so I covered most of the tank with a blanket and I have a heat lamp on one side. It's holding the warm side at about 85 so far and the cool side is around 75. Will my girl be alright like that until I can get a replacement?