My ph is 8.0 and the water is high on the hardness scale. I know that kribs like up to 7.6, I guess lowering it to this wont affect the mbuna too much. Right now the mbuna (I also have haps) are pretty small, as they start to get big Ill keep an eye on them.
It doesnt seem like the krib likes the menu though... Spirulina and Cichlid pellets. It does like goldfish flake.