Will mopani wood in aquarium change ph much?

I recently bought a piece of mopani wood since it was on sale(two for one) so I will be getting two. I have a 10gallon and a 30 gallon. 10 has guppies, kuhli loaches and bristlenose pleco and 30 has goldfish, kuhli loaches and bristlenose pleco. I seem to have had a high ph problem(everything else measured great. Don't have any idea why ph rises so high) so I got some driftwood(woman at store gave it to me and didn't know what type of wood) and put it in my tanks(this was about 6 months ago). The wood works wonders for tank ph but is ugly straight wood that is ugly and in way of decoration so I bought the mopani for better looks. Will the mopani wood change ph well or will I have to keep other wood in anyway? 10-12inch wood piece for 10g and 15-20 inch for 30g. Both tanks ph were in the 8.0-8.5 range before driftwood but now stays between 6.8-7.2. Will mopani be as dramatic? I don't like adding a bunch of chemicals to tanks and prefer to use natural ways.