My 75G Mbuna (Cichlids) tank

My current set up is composed of the following specimens: 8 Yellow Lab, 8 Red Zebra, 2 Maingano, 5 P. Demasoni, 1 Wide Yellow Band, 4 Clown Loach, and 1 Cuckoo Catfish. . I ritually change at least 25 % of the water a week as Cichlids warrant clean, alkalinic (high ph) water, with a lot of circulation. I have crushed coral and many rocks to increase the ph. I have java ferns and anubias to assist in eliminating ammonia. I use two over-sized filters (2 Emperor 400's that circulate and clean 800 gph) to increase the filtration and water circulation. I have a crowded tank because Cichlids are aggressive fish and a crowded tank with lots of hiding spots (rocks and plants) help to minimize aggressive between the fish.