Tdog,
We've tried the Ona Gels in the main grow room with little success. I've found that nothing beats more more MORE carbon filtration. We do, however, use the Ona dispenser in our warehouse area that is outside the grow room to handle any odor leaks from the grow room built inside the main warehouse. For this, they work quite well. They make no noise and can be hidden behind a toolbox or something. This way we can control odor in a public area without having a 48" carbon filter and vortex fan hung from the cieling!