Does the 2x54w gives you a good spread of light over your tank? The BBA issue doesn't seem too related to the CO2 but rather growth issues. When plants stop growing for some reason for so, they make good substrates for algae. Try trimming the Aponogeton and allowing more light to get to the plants (low light but not too low till everything stops growing...avoid shading as you do not have much light left.). Go in and remove as much BBA as possible. Try adding 7ppm of NO3, 1ppm of PO4 and 20ml of TMG right after the water change. Add more current to the tank/reactor and mix the output of the CO2 reactor good by adding some current to the output flow. Having 30ppm of CO2 is not that critical at low light level tanks but that will make sure that your tanks are never limited.