Got mines for a week. In a tank 8x4x30" i would recommend two for better control and power. My one on the end of the tank on high power w1 would create waves around .75" to 1 inch at most. Dont get me wrong, it moves a lot of water but for a tank that size, two is best but i got one just to try it out in comparison to my already existing two koralias magnum8s. Still debating on ordering another since mines is fowlr. As far as noise, you can heard it as a cell phone vibrating...must be also the thin wall of my giberglass tank contributing too.