Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
I would skip the kitty litter. Seems it is the poorest choice among the related products. To get that benefit look into Safe-T-Sorb or Turface.
I like the color of the Safe-T-Sorb best, and I think it would be the best if you blended it with the potting soil.
To avoid the layered look of substrate and cap seen at the front glass try this:
Put a temporary barrier (strip of cardboard is enough) an inch or so from the glass. Fill between the glass and the divider with sand, and behind the divider with soil. When you gently remove the barrier the substrate and the cap should hold their places. Cap material against the glass will hide the substrate.
It will not last, though. Roots, digging fish, anything that disturbs the set up will start mixing substrate and cap.