sand can cause impaction!I would recommend orchid bark or cypress mulch. I used to use a 50/50 mix of coconut coir and play sand, by weight, so it was very little play sand, sand makes me nervous with risk of impaction and i personally am not fond of the coconut coir. Others love it. How old is your Greek? If it's an adult you could use forest floor which is cypress mulch but it's not good for the little guys to walk on. Good luck!!
Ok I'm new to the tortoise thing but chopped alfalfa is okay substrate for my Greek right?