Its funny you say that, cuz I just bought my first live plant, and plan on adding many more! I have a gorgeous piece of wood that I'm soaking to get the tanin out of and I'm going to remodel everything. One plant/piece of wood at a time!
Hate to say it but I don't think you can ever get it all out. I have a little piece (Malaysian sinking driftwood) that my mom had from our aquarium when I was little. It was in the tank probably about 3 years or so, and it's been sitting outside in her garden probably about 5 years. The front of it has faded, and when it's dry, it looks grey. Since I started a new tank and it's a very nice piece of driftwood, I asked her if I could take it. Despite having sat in water for 3 years and in the sun for 5 years, the thing still turns the water orange when I boil it!It's taking FOREVER for the tanin to come out of the wood!! It's been about a week now! How long does it usually take? Is there any way to speed it up?? Super excited to redecorate!