As you can see, the light from layer 2 which is red, casts onto the ground in layer 1. I would like to avoid this. I included the .blend file if someone can please take a look at it.
I’m trying to make sure, there is not too much color bleeding. For example, if I have a blue ocean plane, no bumps, just a flat plane and I put a white boat in it, it renders with a strong blue tint. Even though that’s true light optics, I want to control this and isolate the colors, so I can have a good clean render for the individual objects. I’m not always trying for photo realism.