A lot of pet owners who culture springtails use this as a substrate for them, it keeps the water clean and moist so there is no need to spray it but once a week. Lump charcoal is an one of the best substrate to grow the tiny springtails on. Charcoal also makes a great amendment to any of your potted plants as it greatly increases the substrate's ability to drain and keep mold down.
1 lb. Lump charcoal