I have a Berlin classic mated to a Rio 2500 pump. I've had this on my 90g FO
tank for the last 8-9 years.
this skimmer is not effective or user friendly at all. Just getting the skimmer cup off to empty is a PIA. You sort of have to wiggle it left to right forcefully to dislodge the cup and if it is full then you usually end up with a mess. Since day one, this skimmer has skimmed clear water as pipermurphy has said, but hasn't skimmed much of anything in the last few years unless additives are added to the tank water. I was stuck on this skimmer back then also due to my sump configuration. Basically, I'm not able to place a skimmer in the sump. It needs to be elevated outside of the sump for the return flow. I'm even limited to the size of the water pump that I can place inside the partitioned compartments in the sump. One of these days, I'm going to take some pics of the setup and send them to Logan & Darin to see if they can hook me up with a skimmer that actually skims DOCs! Right now the skimmer runs for oxygen saturation and thats about it.