I got a couple pieces of what looked like nice driftwood, & it leached tannins like crazy, turned my tank to Coffee, at the weekly water change, this after soaking it for a week before putting it in my tank... so I pulled it out & boiled it for most of a week, alternating between soaking & boiling, changing the water daily, in the biggest kettle we have... still it turned my tank blackwater dark, it's been in my tank for 4-6 months, & still turns my water darker than I like before water changes... it's starting to get better... staining was a reddish brown, not sure what kind of wood it is, but the type of wood makes a difference