Hi, it has been 8 months since I had my fish in my 55 gal. tank. I have 4 Guppys, 3 Gouramis, 3 Black Mollys, 1 Zebra Danio, 1 Pleco, 1 Algae Eater ... and so on. As you can see my tank is a little one the heavy side with so many fish. In total there are about 18 fish. I just purchased an Eheim 2028 filter because I read many good things on it. This is how I set it up ... Efimech w/blue pad(bottom tray), Ehfisubstrat Pro(mid tray), Ehfisubstrat Pro(top tray), on top I put on the white pad. I'm not sure if I did anything wrong. I rinsed the media and pads before using them. For some strange reason I have this white type of particles being released from the filter. I had it running last night, and in the morning I found 3 swordtails dead. I am very upset since they were very nice fish. Anybody have any idea on what to do????? Maybe buy something new???? Add something????? Thanks *thumbsups