DRIFTWOOD FOR THE AQUARIUM
To treat uncured driftwood for use in an aquarium, you should sterilize it by soaking it in a mixture of a 1/4 cup of bleach per gallon of water. After soaking in this solution for 24 - 48 hours, you must then keep the driftwood in a container of fresh, clean water for a period of at least a week, with the water being changed daily. (If the wood floats, anchor it down so it is completely submerged in the water at all times.)
If your driftwood floats in the aquarium, use a rock or brick to hold it down in a temporary container, it should soon become waterlogged and sink on its own. This can take up to a month or longer, depending on how dry the wood is.
Driftwood contains a tannin that it may leach out into your aquarium, causing the water to become tinted a light brown. This will usually clear up in time after a few water changes. IT IS NOT HARMFUL. Driftwood may also cause a slight lowering of the ph. Again, it is nothing to worry about.