I have the g4 & works super and it does a nice job, lots of skim ,there is a mod for it, a water control valve.(I never used it)Used to contron water level in the sump . the only problem i ever had was removing the collection cup ...It locks tight but allways comes off . Make sure your sump will have the room it needs because of the large foot print. other than that its one awesome skimmer that runs quiet.I dont think they changed much.