Additional filtration for overstocked 75 g cichlid tank?

I have never had a cichlid tank and just bought a 75 gallon to get things started. I would like to go overstocked with primarily mbunas for appearance and to cut aggression. I have a used Rena XP2 that is used (used to be for a sale tank but assume I can clean out well with hot water to reuse). Wondering what additional filtration I should have or need in addition? Probably another canister right, this way I can just run it inline after/before the Rena? How many power heads recommended for this size tank?