I have one set up on my 150 for polishing (about to move it to my 180) that is running w an xp4 for bio. I can say that after a week of running with the white polishing pads there was barely any flow. I bought mine used for $90 and thought maybe someone sold it real cheap cuz it was junk. 2 weeks ago, i took out the white polishing pads and replaced them with the blue pads in the top 2 trays and the water is still perfect. Yes, it is a big bulky filter to be luggin around every week, but since I figured out all of my media, its an awesome filter. I'm moving it to the 180 and gonna run 2 fx5's on my 180 and add another xp4 on the 150.