Most bogwood is going to leach tannins into the water. How long this will go on varies. Boiling helps but rarely cures the problem. I've had pieces leach for a month, but I also have a piece that continues to leach after 7 years. Carbon will help remove the discoloration but has a short lifespan in the tank so it will need to be replaced often (expensive). If you have live plants carbon is not an option.
In the end the leaching ends up being no more than an inconvenience. If you do your weekly water changes you will keep the discoloration to a minimum.