My Greek tortoise is only 4 months old. It's tiny, only 2.5 inch long. I know it's good to give him a warm bath now and then, but I don't know how you keep the water bath warm. I can not add too much water, because he is tiny. That little water quickly cools down to room temperature within 60 seconds. If I give him a 15 minutes bath, he would be sitting in cold water for 14 minutes. Will that be okay?