I just went through this with some African root wood. The piece I wanted was already in a tank at my lfs but they sold it to me anyway. It had been in their tank for about six months. I went ahead and boiled it anyway in case there were any nasties hiding in there from the lfs and to leach out more of the tannins. The wood didn't exactly fit in this old pot I have but I found by covering the protruding piece completely in aluminum foil, the part that was not submerged was basically steamed. Then I flipped it a few times so the previously protruding piece was not submerged. After boiling about two hours, the water was not that discolored (probably since it was already in a tank for six months). After boiling, I also scrubbed it with a new, stiff toothbrush under running hot water to remove the algae, etc. from the lfs. It turned out real nice.