I'm not using a reactor on my CO2 system so it seems that all three of you recommend the power filter. I am confused on why the Biowheel will out-gas the CO2 and the other power filters do not. Is it just because of the biowheel itself? If this is the case then I will go with the Whisper Power Filter. The reason is because a friend of mine has both the Agua Clear and the Penguin BioWheel and the Penguin is by far more quiet and that is why I was thinking of using that one.