I am setting up a 120 long tank ( 5 feet). I would like to use 2 tunze powerheads but i am confused with all of the numbers. I see alot of 6100s and then there are 6100 with diff pucks making them 6100.2 or something. I have also been told to get 6105s. I am lost as to which ones i should get. I would like to have one at each end of the tank and use a controller for good wave actioin. Please help. Id really just like to stick with tunze.