Hi Shaun. I've found that with these Atomizers, the pressure on the outlet needs to be much higher than normal conditions. Based on what I'm seeing on the low pressure gauge, you need to be between 10-15 psi minimum. I have to go as high as 25 psi on my Atomizer. Is the Atomizer currently hooked up on the output of the filter? If it is, you should see a fine mist coming out of the output pipe. If you're not see it, then you're not likely see CO2 get into the tank.