Sure it`s safe to use.
Just a good cleaning, as was already said.
If I was you, I wouldn`t limit myself to the rock available at HD/Lowes.
Check the phonebook for a landscape supply yard near you.
Great prices and allot better selection of rock.
On your choice of sand, if you have fish that will get the sand bed stirred up, playsand can be a bit of a pain.
The fish will thrash around, dig and spit, and that fine sand could get into your filters.
I chose pool filter sand because of it`s weight.
My Africans can get nuts with it and it just sinks back down.