An undergravel filter has no place in a cichlid tank (or in any tank, in my honest opinion). They do not work with sand, especially fine sand, because it will fall under the plates and not allow any water movement through. Even with gravel, I think that they are crap and trap the very same. The poo and other waste gets stuck under the plates, requiring frequent tank break downs and high nitrates. Even in a reverse flow system, where powerheads are used to force water through the plates and the gravel, a bunch of fish crap (somehow... I am not sure exactly how) gets trapped underneath and creates a mess of decaying matter, making it impossible to keep the nitrates down.
I had a single betta fish in a 5.5 gallon tank with an undergravel filter. It was reverse flow (pushing water into the gravel bed from the bottom up) and I thought that it would keep the crap out of the gravel and on the aquaclear prefilter. I was wrong. One day, I had to move the tank, when I saw underneath it I was shocked "Is all that fish crap". I didn't believe it, but I removed the plates and the water turned a nice chocolate-milk-brown. This was just after 4 months with a single betta. He was on a limited food supply (in an effort to keep the water clean), had weekly to biweekly 75% waterchanges, and thorough gravel vacuumings each time.
I always had high nitrates, until I removed the UGF and got a cascade 80 filter, fitting it with some bluebonded and 5 or 6 ceramic rings from another tank. After that maintenance was a breeze and I got all the crap out of the gravel, easily and quickly.