1. We had grates like that (not the same product though) on our old 180g setup, but that has changed. They do tend to build up with coraline, algae & food products. YES, you have to change the filter pads very often, insure that you keep an eye on the grates, or it can cause your system to not flow properly. I was constantly using a sharp plastic knife to keep those grates open. Something to keep an eye on if you have a filter of this type. ...Angel:angel1: