What Happened?!

OmarD, you have the nitrate in mind, do you not? I don't understand the 36 as much as the old 72. Only thoughts are the bioload being crammed into half the water. Migration to the 30 is going well. Will this help the load, decrease the nitrates? Should I move some of the fish? There are only 6 fish, 4 damsels, 1 hawk, and 1 puesdo. Thanks.
Here is a shot from the 30!

 

I had a 55 set up at a elementary school In Amelia Co. Va . It ran fine for several yrs .. Then one-day the 2 inch remains of 12 inch engineer Goby floated up . Then a Naso Tang and then a few other fish disappeared as did all the crabs and snails. I asked Questions about if anyone had added anything to the tank.. A 3rd Grade teacher said he had been in a LFS and they had something called L.Rock he brought a long flat piece it had all this wonderful life on it the LFS guy told him and All reef tanks needed the Diversity to survive long term.... But that was well over a year and a half ago when I got that rock he said LOL

Well after a long night with a set of Red LED's on the tank and a 12 pack in the main hall entrance about 1:00 A.M I saw the little bugger.. a red shamefaced Crab about 4 inches in Diameter.. He snagged a Huge Green Emerald I had just put in there when it passed in front of his hideout . Snap cut it right in half.. The Emerald was larger then a Quarter little smaller then a 1/2 dollar coin.. I had to tear the whole tank down to get him the next morning

But yes These things can come in on rock and even sand as Microscopic larva