If it is like the wp40, it isn't a speed controll as much as a frequency control. the nob adjusts how quickly the motor turns off and on. If you want to lower the speed of the pump, you need to use a different voltage output. People have been usinge variable voltage power supplys to adjust that point. I have a single wp40 on my 4x2x2 120g and it can make several different sized waves. I would love to drop one of the 25s on my nano tank.











