I have THIS pump and I'm guessing the 2-pin connection on the back of it is for voltage control. On the dangerden website it says that it can be hooked up to a fan controller so you can increase or decrease the voltage to the pump. Now what I've been having a hard time with is finding wiring that will work with it. I've looked at a few online stores, but no luck so far. If anyone knows where I can get a wire for it I'd really appreciate it. The connection on the back is male, so it'll have to be a 2-pin femal with a 3-pin feamle on the other side.