My neighbor gave me about 100+lbs of holey rock. I have been researching Lake Tanganyika for the past few days and heality leaning toward a Lake Tanganyika community tank. Shellies on the bottom, build up rock piles on each side of the tank for Julidochromis for one side, Chalinochromis for the other, 1-2 Xenotilapia Ochrogenys or Enantiopus for the bottom and either Cyprichromis, Neolamprologus or Cyathopharynx for free swimmers at the top.
Sandy bottom with shells, rock formations up both sides, Jungle val growing up the middle as a divider of the rocks. 3-4" of sand, rocks are about 21" tall so that would put the top of the rocks about 24" off the bottom at the peak and leave 6" from the top of the tank for free swimmers.