Yes Aragonite does raises pH, and KH/GH, it's CaCO3 (from coral's and ocean life skeletons). It can raise pH to 7.8 - 8. It's been used for decades for this.
However from my personal point on view, that's not a proper a way to setup an african cichlid tank, even if many people do it.
It will send only calcium in the water and the chemistry of the Great African Lakes is much more complex than that. Magnesium is needed, and many other minerals.
Better use real rocks, like limestone, which will raise pH/GH too, and that will send not only calcium but magnesium and possibly other minerals in the water.
Or better the Seachem products mentionned earlier.
Last edited by micheljq; 07-31-2018 at 06:34 PM.