It makes it a lot harder for them to dig and bury themselves because of the large pieces (I have tried it and did not like it, more suitable for larger species IMO)
You can use coco coir which is a fine grade and it will work perfectly (reptile prime which is ready to use, or echo earth which comes in bricks but will need to be prepared and dyed out before use)
Or Aspen shredded or sanichips.