i set one up about a month ago... i have the outlet nozzles about 14" from the surface, one nozzle is pointing up and one down. the flow from the nozzle facing up breaks the water surface and the one facing down pushes all the crap to the other end of the tank, so i'm pretty happy with it
Can i just say, How quiet are these things!!! i either have to put my hand on it or check the water surface for movement to make sure its on