These were collected from an area that had a fire a few years ago. There are some charcoal on the driftwood. I removed off as much as I could. There are still some charcoal on the wood that I cannot get rid of completely. Is it safe for aquarium use? Here is a picture of the wood.
http://img22.imageshack.us/img22/6834/0601001741.jpg
http://img22.imageshack.us/img22/6834/0601001741.jpg