It was 20 lbs of 2/12 gravel. It s a little coarser than sand, it s what my LFS uses. Acts like sand tho, just won t get in the filters as easily. Also, put Eco Complete under it for my plants even tho they re low light. Just hope their little barbels grow back. Trying to be a good fish owner. The best part was, I finally! caught the lone Penquin Tetra I could never catch, so he s in another tank & will go with me Sat to join his own kind. Was pitiful watching him trying to school with the Oto s.