A couple of days ago I installed a sump to change from a HOB filter and first my pipefish died but now the next morning my goby is dead and my clownfish is struggling. I cleaned out my sandbed during a water change last Sunday but I would think that if it was a bacterial problem it would have showed itself before then. I put my old HOB filter back into the tank with the same media bag from the sump that I took from the HOB and did a water change. Going to do another one tomorrow after I make fresh saltwater. Anything else I can do or that you can think of to help?