I've used EcoComplete in my planted tank for the last 4+ years with good success. Requires little to no rinsing. Might be overkill with what you are planning. Also, the black it is not completely black: (can vary bag to bag) you may see a bit of grey, tan, brown, and red granules present.
You may want to check out Black Diamond Blasting Sand. Very inexpensive; requires a decent amount of rinsing.
I bought some black sand from one of the big box pet stores and while rinsing, I noticed some of the "color" coming off of it. Perhaps I was handling it a bit rough, idk. However, I am using it in one of my shrimp tanks. I use just enough to cover the bottom; 1/8"-1/4"