As I look at more and more tanks I wonder how much tank do you really have. I look at a lot of Nano tanks where about 15-25 percent of the tank is actually substrate and wonder how does it really change the tank. I know with a bigger tank its not as much an issue, but when you have a 1-10 gallon tank and that much is actually substrate how much of a difference does it make. I see plenty of nano tanks with 1-2 inches of substrate and a added approx 1-2 inches of rock, if crushed and laid down. So really how much tank would you have in that situation? Do people really take that in to account when stocking tanks or is it already factored in.