Swimming Pool Supplys! It is used for a filtering media.
I forgot to add...
Be careful when pouring it out of the bag. Diatoms are microscopic skeletons of sea creatures that lived millinnea ago. It isn't really "Earth" and it's not good to breathe it in.
Here is the link to custommilling and it takes 2 days to reach you through the mail. It cost me 50 bucks for 50#'s (that includes shipping) but it's a year later and I'm STILL using it! It lasts forever if you don't over do it.
Swimming pool DE will probably work to deter bugs and for general spreading around the place.
But you dont want to eat it. Neither should birds or animals.
That sort is treated with heat and chemicals and so is not something you want to consume. In small quantities, like with a general dusting to control insects, it probably presents no major problems. Sometimes we tend to blow things out of proportion....
But, because it is chemically treated, there exists the admonition to use only food grade DE. It is completely inert and there are no toxicity worries over it's presence, or it's use. It can be fed to your animals to prevent internal parastites and indeed you can eat it, too. So to avoid potential problems, it is the best sort to have.