It's the Wood bud, I have lots of driftwood and lots of tannins! I use a bit of carbon after its in the tank( takes a few days and it clears) but for the smaller pieces, I did boil them and soak and boil, but the tannins aren't harmful at all to ur fish. The tannins actualluy soften and lower the PH( if that's what you need/want) hope this helps.
