Well, your nitrite should be at 0, and if your tapwater's nitrAte is 0, then a large water change can bring the nitrate level down quite a bit.
While I've seen some very odd tank mixes work, you'll need to keep a very close eye on yours. Most mbuna (rock dwelling african cichlids of Lake Malawi) reach sexual maturity at around 2 inches. While they can be very peaceful as juveniles, once they reach maturity their aggression levels can change literally overnight. They are also harem breeders, where you should have 3 or more females for every male. These are not pairing fish, and eventually a male will severely stress a single female if she isn't ready to mate when he is (read all the time
). You'll want to watch the mbuna with the angelfish and bala sharks as well, they are both fairly peaceful species and may get picked on.
Then, there are the convicts, they are pretty peaceful as juveniles and may get picked on by the mbuna, however, once the convicts decide to pair off and start breeding they can easily dominate your tank. There are keepers on here that have had a pair of convict decide an entire 6-ft tank is their territory and beaten up or killed off fish many times their size.
Aggression aside, you also have vastly differing feeding requirements. The mbuna are herbivores, because the have a long intestinal tract to break down vegetation, too many meaty foods can give them bloat. The angelfish and convicts however need the protein from meaty foods. You might be able to get away with feeding spriulina and a staple food for african cichlids and then suplement weekly with frozen brine shrimp for the other fish, if you can find spirulina enriched brine shrimp that would help.
You do have a lovely tank, and please don't think I'm trying to kick sand on your picnic, just pointing out the things you need to keep an eye on. -Dawn
