Bogwood—wood that has been either submerged in peaty water or buried in boggy ground for a long time—helps to give the aquarium a more natural feel. It also provides an attractive growing medium for plants such as Java Fern. It is especially suitable for aquariums where soft, acidic water conditions are required.
Bogwood contains tannin, which will leach into the water and turn it brownish-yellow. The tannin is not harmful to fish, but it spoils the appearance of the tank. To prevent this, pre-soak bogwood in a bucket of water for several days. Change the water each day, and scrub the bogwood with a clean brush before adding it to the tank.
Driftwood can be treated in a similar manner as bogwood. You can also boil driftwood to disinfect it and accelerate the removal of any tanins. Driftwood may also need to be cured by allowing it to soak in a bucket of water for several weeks until it becomes waterlogged.