Originally Posted by Jakusonfire
There is a limit to how low you can have the voltage before the pump won't start or won't run. Its quite high like 10 Volts
The speed dial on the back of a D5 vario does not reduce voltage to the pump like a simple pot. It is a more complicated motor speed control circuit.
I'm running into a pump noise situation on a new EK DCP 4.0 pump. Did a quick test by hooking it up to the fan controller and the noise at 10V was definitely manageable. A huge difference in noise between 12V and 10V (w/ 8V being near silent).
Had to order a pump controller to control the noise. Wondering if I should have just gone with a D5 vario pump in the first place. Might have been cheaper in the long run...