I've had in in my 40 (see link in sig line) for I think 5 mos. as a Cap over MTS.
I had Black Diamond blasting grit but it was to dark. Initially, I liked it, after a month the fine sand settled and I have small gravel. To get a better look, I syphoned off most of it in the front leaving a few patches of the sakcrette. I used play sand to replace it.
I like the current mix better. The low spots have more light gravel, higher spots fine sand. Which is what you would see in a stream. For what I want my "scape to look like it's a good mix.
As far as the All Purpose Sand, I didn't feel it was excessively dirty when I rinsed it prior to use.