Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
Never heard of Temisca silica sand, but if it is used for swimming pool filtration, I cannot foresee it being anything else than non-soluble, completely inert silica sand, preferably quartz-based. Check with the supplier to confirm that it is in fact completely inert, and will not leach any material of any kind.
If so, you're ok for aquarium use. The PFS I get and have used for several years is # 20 grade white quartz-based silica sand, and it does have dark (black &/or slate grey/charcoal or brownish) bits in it - which gives it a very natural look when spread out in water.
Your white example above looks larger-grained than my #20 grade, but perhaps that's just the closeness of range of the photo. Even if it is larger, that would even be better, in terms of density to prevent it from being easily disturbed into the water column, &/or unnecessarily siphoned up.