Aqualine Buschke membrane reactor double, CO2. The Aqualine Buschke CO2 reactor does not dispense CO2 as a gas bubble into the water. It is rather diffused through the membrane tube directly into the water. The membrane tube consists of a special material which lets gas but no water through. This acts simultaneously as a check valve. The CO2 gas gets through the tube and dissolves on its surface directly in the water. Double reactor good for aquariums up to 100 gallons.