I`ve read about aquarium tops with Co2 injection having " very tightly closed tops " to keep the Co2 loss down a bit . Can anyone share with me how this is done ? I have Tidepool siphon on the back of the tank and for the life of me can`t see how I could have this top tightly closed . Not even with a wet/dry on the back . What`s the trick ? DT Wilmington Ohio