I have an Aqua C Remora skimmer on my 30 gallon system (20 gallon display and 10 gallon frag tank) and it doesn't seem to be pulling much stuff out of the water. I also did a routine measurement of all of my parameters and it appears everything is as it should be: Ca=440ppm, Alk=10dKh, Mag=1360, Nitrates and Nitrites=0ppm, and PO4=0. Should your skimmer be constantly pulling stuff out? Or are there times where it won't pull that much gunk out because the tank is actually how it should be? There definitely is buildup of gunk in the tube leading up to the collection cup. But it doesn't seem to bubble as much as it used to and there is hardly any liquid in the collection cup. I find that odd for some reason...