I got substrate called "Lizard Litter" the description says "Terrarium ground cover for all lizards, snakes, turtles, tortoises, and arachnids. Bacteria and parasite free. Easily digestable. Nontoxic. Ultra Absorbant. Ideal for tropical, forest, and desert habitats." They said it was made from a plant called Kenaf and that it is not wood or bark.
Also I made the rosehair a burrow out of a toilet paper roll covered with substrate on top and IO cleared the substrate behind the roll so that I can see into his/her burrow. He/she is a sling and it about 3-4 inches long. What instruments should I use if I want the spider to move? What do you keep the crickets that you are going to feed to the tarantula in?
Also, you don't necessarily have to make a burrow, as not all rosies burrow. Just provide a hide of some sort and position it so that you can see her. I have tried Lizard Litter, and I found that it works well for rosies.
Everybody's buying rosehairs! nice!
Pategirl covered the sponge, don't know that substrate, so can't comment on that. Actually the only thing I have to say is that 3-4 inches is not a spiderling anymore, I think a rosehair of that size could be adult, but more likely a juvenile.
Succes with your new spidie