Planted Tank Enthusiast
Join Date: Mar 2010
Location: Fairfield, CT (USA)
Take the biggest stone, stand it more or less up on its end, and angle it outward to the left. Do the same with the 2nd largest stone, but to the right. The 3rd largest stone can be angled from the front left upward to the big stone one the left. The smallest can be closest to the front, more or less centered, and as a horizontal foil for the other stones.
That probably doesn't come across well in my explanation, but I'm a visual person, not a direction writer :P
In an ideal world you'd have 5 of these stones - you always want to place larger/focal stones in odd numbers if you can.