Tile Bottomed Tank

[Nano_reeflover]

I remember reading about someone on here that used tile in the bottom of his tank. He used sand to act as grout between the tiles. Are there any pics of this? I would like to do the same thing using these tiles:
http://www.contractorservices.homed...0872&pid=5f1f0755-cb8e-4739-8e7e-ea0ac4b4c81d
or this:
http://www.contractorservices.homed...0872&pid=1bcf6214-a3da-4fa6-b030-aadecef8092d
Is it safe to do? Any help would be appreciated.