Heating and Temperature are very important to the health of your Geckos. Geckos as in all reptiles need heat to thermo-regulate, as they do not produce their own body heat internally. They need an external heat source to help them digest their food as well as regulate other bodily functions,temps should remain between 80and hot spot 95.i would recommend you use kitchen towel at the present time it doesnt look so attractive as a sand substrate however its much safer