Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Sand does not usually stick, unless there is something to make it stick, some sort of gooy stuff.
Very small live animals might look a bit like sand, but cling very well to the glass.
Look up Hydra, for example.
A fine cloudiness on the glass, but you cannot see bits of anything might be certain species of algae. This is usually a green algae, but at first you might not see a color, just a sort of fogginess when you try to look into the tank.