for african filtration i recommend having 6 times the tank volume so if its 400l that would make 1600lph, i have found that to be plenty even when over feeding.
the tank at the moment looks quite dark to me, i would lighten the background to a pale blue or navy blue perhaps and have a white substrate. I have crushed white marble as a substrate with a navy blue background and it shows up the duboisi and black pemba very well. I also have leleupi which are bright orange, they add a great colour dimension to the tank.
i would also add more rock work at either end, the tank looks tall from the pic so would be trying to make the tank appear longer.
i have tried plant and sunlight bulbs on either half of my tank at the same time, the sunlight ones made the tank look far better.