Hello, I inherited a Fluval 404 with a 90gal tank and it had been running fine, although it hadn't been cleaned in a while. I finally got the time to take it apart and learn to clean it and then put it back together, and now it is making a horrible humming, rattling noise constantly. I'll try and take it apart again but does anyone know what to do about this thing? I've seen other people having this problem but have found no follow ups with what to do or what is causing it.
thanks
thanks