In my opinion, unless you are set on having a skimmer cup, the best option is a 9010 and add the 9020.14 drain tube. This will outperform a 9015 and costs about the same. A 9010 and 9015 only differ in the cup, which since it doubles as the foam reaction chamber allows you to open the venturi more on the 9015. The 9015 skims very dry, the 9010 can skim very wet, if you add a 9020.14 to a 9010 you get the ability to run the venturi full bore open and get a wetter skimmate which tends to be more effective at PO4 removal.