You can control it with pmw. I'd imagine it could be 0 - 100ml/minute.
Next project to control with the arduino.
I noticed it could be controlled with PWM too, but it doesn't necessarily mean that the minimum flow rate is 0 mL/min...does it?
For example, the one on eBay has a minimum flow rate of 0.1 mL/min (which I guess is as close to 0 as possible).
In any case, autodosing was part of my plan for an Arduino based aquarium controller