We went to Petco today and couldn't resist temptation to but a couple of pieces of driftwood that they had in a Koi tank already sunken. I think we paid like $3.49 each for them. The catch--they have a type of algae all over them. I think it's a type of black algae, but I could be wrong. I haven't really checked it out much. I would have liked to check it out there at the store, but the "fish guy" would not let me touch it and it was super dark in the tank that it was in. Still, we brought it home. Is there any chance of me killing this algae and not having it come back? It's nice looking wood and it doesn't even float so I hope so!