I have 2 110's on one of my 55's, one for each UG filter plate. The intakes are in the UG lift tubes. The area under the plates stays clear, and whatever doesn't get siphoned during partials collects in the sponges. I use 2 sponges in each, and rinse them out when they become dirty. I've been using the same sponges for several years now. The rings serve the same purpose as the sponges, providing surface area for bacteria to colonize, but I don't use them, since I have an UG filter. Incidentally, the 110 pumps 500 gph
, so I'm turning over the volume more than 20x/hour. Gravel and rocks take up significant volume, so the actual water volume is always less than the tank size.