I know but you can take it out of the line and place it in front of your pump,
i did try that once before, but since opting for a Co2Art in-line system i have noticed a significant level of mist bubbles coming in to the tank via the nozzle (felt that maybe most of the bubbles were escaping to vent out of the sump than going to tank. I also put a 2m length of hose after the in-line unit which i think helps the absorbtion in the transfer into the tank. The pump appears to cause quite a return flow by itself and i have it helped it with two Powerheads. I have ordered another to place at the distant end of the tank to further assist the circulation current. Im conducting a PH Profile today and hope to see an improvement on the plant health over the next week or two...