Pull that Mopani out ASAP if you only soaked for 3 days! You will have yellow water for years! I have a lot of Mopani wood & I've done this several times now. It works very well.
1) Boil the Mopani chunks in a large stock pot of saltwater for 3 or 4 hours to extract the tannin & sap.
2) Repeat step 1 until the water is a light tea color
3) Throw the salty chunks into a large cooler or bathtub of very hot freshwater to soak. Change the water out with new hot freshwater every few days. The salt will leach out the last of the tannins.
4) Put your disinfected, de-tannined & de-sapped wood into your tank with carbon in the filter. Water will still turn light red-yellow for a few weeks.
