Here are my recommendations:
1.) I wouldn't recommend sand. Eco-Complete for cichlids would be my recommendation for substrate. Sand will plug your ugf and at a depth of 4", could compact and deter water flow over the bio-bed. The addition of a canister as you were recommended will not solve the problem of "ammonia hot-spots". I have never heard of that in 46 years of keeping fish. You will kill the bacteria in compacted areas. Plain and simple. This will cause a deadly and dangerous situation. Methane gas has the conditions it needs to form if this happens. And methane is explosive, my friend.
2.) I would use (4) reverse flow power heads. Marineland 660r's or Marineland 1140's with reverse flow adaptors would be the product of choice.
3.) If using a ugf, you will need to make a modification. I use plastic "egg cate" light diffusers on top of my filter plate. This prevents the cichlids from digging and exposing the plate and compromising the filter bed.
4.) More filtration. Use (2)Emperor 400 power filters, (2)Magnum 350 canister filters, (2)Fluval 4+ internal power filters, along with the RF powerheads and ugf. This allows you to add more fish and help keep injuries due to aggression at a minimum.
5.) Get a couple of hospital tanks cycled and running. You gonna need them.
6.) Provide plenty of rockwork, caves, nooks and crannies.
The "multi-layered" filtration system is described in the attached link. http://www.fishforum.com/viewtopic.p...hlight=#112001