I am going through the same waiting/soaking game with my Mopani wood. I was reading up on filtering methods to help remove tannins and Seachem Purigen comes highly recommended. You just add it to your filter media and it pulls most of the tannins right out of the water. I'm going to pick some up tomorrow and try it. I will be doing a large pwc
and adding my Mopani wood tomorrow. I'll let you know how it goes.