Any Pool Filter Sand will be safe…
Rinse it well before putting it in the tank… “silica dust’ will not be a problem since you rinsed it before putting it in the tank…
Pool Filter Sand is regulated to be no larger than X and no smaller than Y… yet naturally due to grinding there will be some dust that needs to be rinsed prior to use… Different brands may use different regulations, but all will be fairly uniformed in size…
As for silica or non silica… it doesn’t matter…
Please educated yourself on what silica is before misleading anyone on this…
The chemical compound
silicon dioxide, also known as
silica, is an oxide of silicon with a chemical formula of SiO
2 and has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms. It is a principal component of most types of glass and substances such as concrete.
http://en.wikipedia.org/wiki/Silica
So unless you believe that sand, glass, silicon, quartz, etc are bad for your fish… silica is fine…