Greetings. There is a lot of info on all of the introductory pages here on the Forum. You won't find rabbit pellets listed anywhere as a good substrate. Most torts require high heat and high humidity. Under these conditions, rabbit pellets will quickly get fuzzy with mold spores. Think cyprus mulch, peat moss, and / or orchid bark. Coco fiber provides real nice substrate as well. Not sure what kind of tort u have, but rabbit pellets arent the way to go.
I really like coconut coir and also have leopards. It holds humidity well and won't mold. Most likely whatever else this person that said to use pellets told you is probably wrong too. Please read the links below in my post. The sulcata threads will work for your leopard too.
You have to first learn what your tortoise needs, and then try to provide that. So there really isn't a one-size-fits-all type of substrate. For baby leopard tortoises my substrate of choice is small grade orchid bark. Where I live, in a dry, hot climate, the orchid bark works very well for me. I pour water over it about once a week to keep it wet and I cover that habitat to keep the warm, moist air inside. Works just fine for me.