There seems to be some debate as to whether or not the atomizers save CO2 or use more. That said, the initial rush of bubbles is due to the large pressure differential between the regulator and the CO2 line. As the CO2 line fills up w/ CO2, the pressure increases and the bubble rates drops because there is less room to add more CO2 bubbles. Eventually, the line pressurizes to the minimum pressure needed to extrude bubbles from the atomizer and then the bubble rate is equal to the rate of CO2 diffusion / extrusion.
So, this is normal. I thought somethings wrong with my set-up.
The more bps I use the more large bubbles are released when solenoid is open the next day.