Can I add a finer substrate on top of this?

[we4wieners]

I would love to add some tahitian black or some fine black substrate on top of what I already have. I only have a layer of the existing substrate, not deep at all. If I add sand, will it just sift itself through to the bottom and be lost.
I want a black substrate bottom, finer than what I have now. Here is what I have...
Should I just dump a couple of bags in after rinsing...?

 

[Egon]

If you add enough sand it will cover for sure. Definitely rinse the sand first.
If your not in a hurry you can suck that sand out with your weekly water changes. Just run the hose down there with out the gravel vac attachment, it will suck up the gravel. It might take a couple weeks with 10% water changes, but you can get most of that sand out. Covering it is easy though.

 

[knifegill]

It will cover at first with sufficient quantity as said above, but once you start vacuuming and stirring you'll see more and more pebbles on top. It'll look neat, though.