Yesterday my friend called to inform me that my whole tank had suddenly died. When I say all dead I mean all dead, copepods were stuck to the glass, worms had crawled out onto the sand bed, the fish, hermit crabs, starfish, and snails, it was all dead. The only thing that survived was a puffer fish. He was immediatly put in a quarantine tank and is doing alright, though he still doesn't look well. Water parameters came back fine, water was at 75deg, pumps never stopped runing. The fish in the tank were a coral beauty, sailfin tang, lion fish, and puffer fish. The tank is a DAS 110. It has roughly 100lbs of live rock in it and a sand bed of aprox. 2in. The tank has been set up for about 5 months now and has had a Horrible hair algae problem for the last 3-4 months. My question is why did this happen? Any ideas would be great as this is a horrible loss of life and don't want this to ever happen again.