I finally got my co2 setup into a powerhead and I have decent mist going through out the tank. But I do have some co2 bubbles floating at the top of the tank is that bad? The circulation is a lot better on the bottom of the tank than the top because my powerhead is about 1/4 the way up from the bottom of the tank. If so how can I fix. Tank is a 20Long with a powerhead back right corner right above the diffuser and it shoots it left into the flow from the HOB filter and circles back around.