Using activated carbon Bounce
suggested and water changes-is about all you can do until the wood stops leaching large amount of tannins. I had to use some short term in one of my soil based tanks due to the wood I used last year myself. It took about a month before it stopped leaching large amounts of tannins and water logged...lol.....Then I stopped using the carbon.
You will need to change out the carbon weekly-depending on the quality and amount you use-along with 50% weekly water changes and if your tank is glass-you can use a razor blade to remove the tannin stains off the viewing walls-acrylic tanks can be a challenge to get them off-
The tannin stains on the viewing wall can sometimes make it look like the water is much darker than it really is.