My son had a 5gallon reef tank with a clown, blue damsel, half yellow and pink fish. All the corals had died out and the tank was looking pretty bad. Today I moved everything to new 29 gallon tank. I took out the liverock and cleaned it with an tooth brush. I later found this site and was amazed how poisonous and dangerous these stuff could be. I guess I shouldn't have been moving the rock and sand with my bare hands. Does it matter that I no longer have living corals in my tank?