Driftwood makes a wonderfully natural addition to aquarium decor, but it comes with some risks. To prepare driftwood for an aquarium, you must destroy any bacteria or organisms that may exist on the wood before use. The method is extensive but simple.
Spray the piece of driftwood you intend to use as decor in your aquarium with a high-pressure garden hose. Be thorough in spraying all nooks and crannies. Use a scrub brush in conjunction with the water hose to scrub off loose pieces, algae and mouldy parts.
For small pieces of driftwood: Fill a large pot with water and bring it to a boil on your hob. Place the driftwood in the pot so it is completely submerged. Boil the aquarium driftwood for about 1 hour to kill off fungus and bacteria that may be inside the wood. It also will help leach out tannins that may discolour your aquarium water.
For large pieces of driftwood: Place the driftwood in a large bucket or tub. Boil pots of water and pour over the large driftwood pieces. Add hot water until the driftwood is submerged and soak for up to 1 hour. If the water becomes very discoloured in either of the above steps, dump it out and replace it with fresh water for another boil or soak.
Soak the driftwood piece for an additional day or two to completely saturate the piece of wood. This will prevent the driftwood from floating in your aquarium. At this point, add the appropriate amount of fish tank dechlorinator solution (available in pet stores) to the amount of water you are using. The amount varies slightly among formulations, so read the directions on the bottle.
Place the driftwood in the aquarium. If the wood still floats, tie it to a rock or two in your fish tank with monofilament, such as fishing line. You also can screw driftwood to flat pieces of pre-drilled slate that you can hide under the aquarium gravel or substrate.