I have searched this forum for substrate and it is recommended to use fine grade orchid bark or coconut coir. Is there a brand that you recommend? Do these substrates have added ingredients that are harmful? The coconut coir comes in a brick so I assume you add water to soften it. How much water? Does anyone have any other advice on brumating a desert tortoise in a refrigerator? I have been given a 3 yr. old desert tortoise and this will be my first winter with him. Want to do it right. Thanks so much