I just purchased the Tunze 6100 with controller 2 pump configuration. I have a 300 gallon tank that is 96 by 24 by 30. I placed them, for now at least, in each of the back corners facing at the front glass at a slight angle so it is bouncing off the front glass and then circulating. I believe I saw that Roger recommended in one post to put them at opposite ends on the side but I did not like how you see them sticking out there when you look from the side but will do that if it is best for the tank. I am a "newbie" of sorts to a reef tank (have had fish only tanks for many years) so I really appreciate your advice.