Surface Agitation And Proper Ph Concentrations

I recently upgraded my CO2 to a dual output system in order to get better dissolution in the tank (Rex Griggs reactor and in tank ceramic diffuser), I can get the pH to drop the 1 degree by the time the lights come on. However, in order to combat the surface scum that prevents the exchange of oxygen/co2 I run a powerhead that pushes water across the surface, the inhabitants seem to be much happier, swimming more vigorously. My problem is if I turn the powerhead on to provide surface agitation my pH goes up almost to the point it was the night before. How important is this surface agitation? I have set it to do 30 minute increments to see the effect on the pH/CO2 concentration. I had not realized that the surface agitation would off gas the tank nearly as much as it has. would maybe 10 minutes in 2 hours be sufficient water movement across the top of the tank?

 

even though those would be great solutions, I don't want to put anything else inside of the tank as there is already enough in there taking away from the natural look of the tank. Additionally, I would love to add an overflow, but it would consist of cutting the hood to fit it in and I don't want to do that at this point.

I have come to realize that the JBJ bubble counter has failed and is not allowing co2 through hence no additional CO2 coming out of the ceramic disk. Contemplating changing over to the hose adapter and using an inline bubble counter.