Im on a constant search to find the best substrate-I was using Hay and the eco earth-coconut stuff that expands-I had to take the hay out because it was getting moldy under the small water dish-my russians seem to like newspaper-I just put pieces down flat and they love to go under it. Im thinking of putting that and the square coconut cubes in when I clean the their habitat again-any suggestions or preferences-I have found that the calci sand and coconut cubes work well for my leopard but I dont have enough sand this week to put in the russian tank. I would love to hear what others are using for substrate for russians and Leopards.