Sick Fish - Can't solve the problem

[Jaws]

So I had all the fish in a 400G display tank plus I had 300G of volume downstairs in my fish room conditioning of sump/fuge/rock tanks. When the fish became ill I drained the 400G, caught all the fish and brought them downstairs. They're evenly distributed between the downstairs tanks now and the display tank is closed off from the rest of the system for now. The main display had all the cycled live rock in it and the rock tank downstairs had the 30 pounds of rock in it that I suspect caused the whole problem to begin with. I removed the live rock a couple days ago when I started worrying that could be causing the problem.