I also reccomend aquatic systems design. I have the dual chamber model with eheim recirculation pump. As far as other stuff needed, here is what I have for my setup: supply pump (maxijet or smaller), CO2 tank, CO2 regulator, solenoid and bubble counter if the regulator doesnt come with it, and pH controller. Basically you plug the solenoid into the controller and it shuts on/off the flow of CO2 to maintain a desired pH level in the reactor. The bubble counter just lets you see how much CO2 you are dosing, and the regulator has pressure gauges and valves to adjust the amount of CO2 you dose.
When I started talking to Scott at ASD I knew nothing about Ca reactors. He made me a list of everything I'd need and I bought everything through him.