Hi. I have a AM1000 and also an Eheim 2217. CO2 is so important in the system that I didn't want to have it relying on the flow through the Eheim, which of course becomes progressively worse as the filter starts to clog. So, I purchased a seperate external pump (an Aqua Medic Ocean Runner OR-2500). As this is an external pump I simply mounted it underneath my cabinet right next to the AM1000 and have a good constant flow through the AM1000 at all times. Works great!
Scott.