I have some questions for you guys that have these powerheads. I was wanting to use 2 of these in the tank I'm planning (36x36x27). I am wantin to have the powerheads on the back of the tank (blacked out). I'm concerned with the fact that they don't have any directional control. It is too much $$ going with the Tunzes that would do the same thing usin a controller. What's the opinion of u guys that have mp40's, will they work since they really won't be aimed at my rockwork. The current will have to hit the front of the tank and then bounce back into the corals. My other option is using mag koralias or two seaswirls but I like what I read about the vortechs. Any thoughts/suggestions?