I have a 50 gallon reef tank that has been up for about 10 months now. Everything has been going wonderfully. Splitting mushrooms, ricordia, and xenia regularly. Deep sand bed, protein skimmer, UV filter, 2-96W PC's. About a week and a half ago I came home from work and my bi-color blenny was dead and the only other fish in the tank, a tomato clown, was almost dead. It died about two hours later. All of the xenia was laid over and dying, all of the yellow, brown, and other polyps were contracted and extended as if reaching for light. Ricordia same thing. Mushrooms shriveled. All of the Xenia died two days later and right now all of the others look the same. All of the hermits have died but most of the snails are still living. All of my chemical levels test perfectly. The PC bulbs are only about 5 months old. Temperature is within the normal range. No algae blooms. Nothing new introduced recently. My first thought was a bacterial infection, but it happened so fast to both the verts and inverts that I doubted that. HELP!