Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
The rocks look like they are different species of rock. A couple are angled, sharp, chipped. The others are rounded. Usually this is not as common in nature. When the rocks are getting exposed in a hillside as if they have been underground for many many years, they usually look like they are all the same material, and are often angled, chipped. If the rocks came from a wet place they are almost all tumbled, rounded and smoothed by the water. In nature, which is large, you might find different rocks near each other, and the contrast shows. In an aquarium, a small slice of nature, it usually works better if the rocks are more uniform.
Similar rocks can work if they are mostly hidden by plants. A bit of color shows through, or an edge here or there. Then you cannot tell if the rocks are the same. These are similar enough for that use.
Anyway, the layouts:
You are using the same layout on the left each time. I would rotate that one vertical rock so it is aimed toward the middle of the tank, not out the side.
Then make the angled rock on the right at the same angle, but yes, out the side.
This way it looks like they are parts of the same rock that is getting exposed gradually as the soil erodes.
Once you have those two placed, and try them more to one side or the other, closer to each other, farther away, in front of/behind each other...
... then place the other rocks.
As two equal piles of 3 rocks the layout is too symmetrical.