I use an Adafruit PRO Trinket for the PWM controller with a 10 turn potentiometer connected to 5v,Gnd, and Analog In "1" (A1). The output PWM pin then just goes to an SSR-->pump. I also use this little chip to operate the element in manual mode. I can expand this to operate as many as 6 PWM devices (only because the arduino only has 6 PWM pins). Here is my simple code if you're interested TRINKET_PWM_CONTROL_V2.Also any particular pwm controller that you would recommend and how would I use it to test the pump before I complete my electric build?