I have some gravel that is pretty big. Some of the bigger pieces are around and inch long, but the average looks like about half an inch. It is a darker tone than most standard gravel and I (my mom) really like the looks of it. The only problem, I want this tank to have lots of live plants. I could take some Caribsea Flora-max and put that in as the bottom layer, and have the other gravel as the top. The only problem with that is that if the Flora-max works its way up and shows through occasionally it would look horrible (It has a rich red color compared to a natural earth tone). My second thought was to take sand as the first layer, with the gravel on top. I would personally go with sand, but my mom says she likes the gravel and since this tank is where people see it easily, she says what goes. Thanks!