There's no difference in water parameters in sump and the display tank. It's 0 amonia 0 nitrates and below 20 ppm nitrites. I'm running a 3200 GPH wave maker and another 1500gph power head inside the rock work to get the flow going. I got a 200gal skimmer and currently running on 4 20,000k 20w high power LEDs.
I've added emperor juvenile, pecular clown, gold headed goby, sweet lips, Indian trigger. All of them died in a similar way. Now there's 2 damsels, 3 dancing shrimp, 3 boxing shrimp, 2 cleaner shrimps, couple of brittle stars, clam and LT animone all doing fine.
Once I did see a small mantis shrimp in the tank (i dont know how it got in) and time to time I can hear the clicks he makes but I doubt it can kill this many fish. Even if that's the case it will be impossible to find the fellow because of the rock work. It's about 130LBS of live rock in the display tank. :S