Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
If it is in fact used as pool filter sand, it is not very 'fine-grained', but nonetheless it should be 'fine' to use, if you get my meaning. It certainly appears dense enough, and with no silt/dust, so should be clean and need little or no rinsing.
Give it a try - I think it would be quite OK. And it's a great color for producing a 'natural' look.
I would very likely use it myself, and not be concerned about using it as a substrate.