How high is the wave you are getting? when you say you are not ahppy with the flow do you mean overall in the tank, or do you mean the wave as I would not expect it to currently be more than 1"? From my, though somewhat limited hands on with the wavebox, I would suspect with a tank of that size an added Wavebox Extension might work out for you if you are happy with the flow from the closed loop and was hoping for more of a wave