BTW, this is more of a personal opinion so plz feel free to take it or leave it. Some red cabomba in the back corners would really add depth to the tank (not that it isn't already interesting and beautiful). A flash of red would go well with the green, black, and stone. Just about anything that gets some height would be a nice addition plus it might be able to cover the pumps. But like I said if you left if the way it is it would still be awesome, just something I would probably do if it were my own aquarium.