How often do you feed your Mbuna? I am presently "recycling" a relatively new tank. Was feeding twice a day. Have cut it down to once a day to try to get Ammonia levels down as bio filter catches back up.
I like twice a day, but I feed very little on both occasions which like you mention helps to keep nitrates low.
Your fish will tell you if they are getting enough by there body shape, just keep an eye on them.
Nothing worse in my opinion seeing fat overfed fish.
I've switched from once to twice a day. I was having a problem with the fish being scared so they'd hide when I'd come by other than feeding time. Now they think I'll feed them. I water change weekly so I've been keeping the nitrates under control.