i have the eheim pro and was told to steer clear of the ecco as they are fiddly to operate and make more noise.
connections i think would be similar to mine. theres an in and an out tube. the in tube is connected in the tank to the intake. the water goes through the filter media and is then taken out and travels in to the tank via a spraybar. i can only go by what mine does as i havent seen the ecco, but hopefully its the same principle.
i would also reccommend the pro as it is very quiet and theres an adjust lever so i can alter how much water goes in.
hope some of that at least made sense
the fluvel range are also very good as well.