Mopani wood has MUCH more tannin (usually) than malaysian. It will reduce your pH noticeably & soften the water very well
SnakeheadTwistedPenguin;3477520; said:If your kh is high you could fill the tank with wood chippings of all kind and it's not going to soften it even the least bit. So you really should test the kh of the water 1st.
What fish are you trying to soften it for? Almost all fish will do just find in hard water.