With the spray bar I seem to get even flow with some very gentle movement of the plants. I suspect that the 700 gph pump delivers much less then that given the four foot rise. There was a chart with the pump, I could look it up. Water movement at the surface is said to facilitate O2 transfer, is that true for CO2 as well?
@steagle: look into Pfertz. They are a little more expensive but I think are still having a sale. VERY easy to use, and seem to get favorable reviews here and elsewhere.