depends on what you are keeping too. i keep everything. some might say i am over'flowing'. the fish behave normally though, they even seem to enjoy playing in the currents and i suspect it may make them stronger. at some point this much flow behaves diffently than streams of water. it is more like walls of movement pushing back and forth and swirling.
tunze 6080 (2250gph)
mag 9.5 return (950 probably adding 700 to the tank)
4 MJ1200s on alternating cycles (600 at any moment)
i could get by without the MJs entirely but i use them behind the rock mostly, and to confuse the 6080 current a little.
if you are looking to add more buy the tunze 6080 you wont regret it. or better yet the 6100 if you want to upgrade tank size and use a controller in the future.