Well here's what I suggest: for powder soil, buy the special kind or don't buy anything. Power sand is one thing that is something that's supplemental, not really necessary. But if you are going to but it, get the special because that has fertilizer in it.
What I would recommend is to buy 2 9L bags of amazonia normal and 1 9L bag of powder. It will cost a little more, but it will look better and greatly improve the adaptability of carpet plants. For the river, either buy a 2L bag of La Plata sand or just go with PFS.
My Golden Rule of planted tanks: WWTAD-
"What would Takashi Amano do?"
RAOK Club #69