Can someone explain to me how gravel, which I would think has much larger particle sizes than sand, is anaerobic while sand is aerobic?
Needs more than gravel alone to cause ANYTHING...........I can grow plants fine in plain sand, we all can..........or gravel. Gravel would have less anaerobic conditions than sand, there's less to block flow between the lower layers.
She also says:
She was referring to gravels larger than a certain size, NOT all gravels. From "Ecology of the Planted Aquarium":
One of the very important aspects in Diana's book is the explanation accompanying its recommendations. Together those explanations help people to think through a situation. People are no longer restricted to paint-by-number. Because of the explanations, people can apply what they've learned to a wide variety of situations.Some tank scapes it would not matter though.
But in general, this is correct.