Do you not have a large CO2 bubble build up under the lid? Kind of like what happens when you inject co2 into a canister filter? Did you adjust your bubble rate any when you went from a PVC reactor to a Cerge reactor?
Nope left the bubble rate the same, drop checker jsut get slightly more yellowish then before, flow is probably 20% greater though as it was picking up all my IAL that were on the bottom of the tank and blowing them around which never happened with the Inline PVC Reactor. Only time I have gotten a build up was yesterday when I had the filters off but forgot to turn the CO2 system off with the tank mostly drained for 2 hours while catching out my Albis. It went away about an hour after the filters were on, the water comes in at the highest point in the filter I'm using so any CO2 that would build up is constantly meeting the incoming water so I don't see it being possible to build up much excess CO2 there.
The fish didn't mind the slight increase in CO2 so I just left it turned up, I could probably turn it down some but don't really see the need unless I absolutely have to.