I was wondering about that! Yeah, its just shy of two cycles an hour but I think its fine. Do you mean the reactor needs to be in the tank when using a power head? I was thinking of running hose from the outlet of the pump, out of the tank into the reactor, then more tube bringing it back. Would this not work? I only went for the in-tank reactor because it was easier to build, but now I have decided to get a bigger reactor, I want to move it out of sight.