You need to get a drop checker, fill it with 4 dKH distilled or deionized water, and use it to determine if you have enough CO2 in the water. With that much light if you are close to 30 ppm of CO2 you will have fewer problems with algae. The bubble rate just allows you to maintain a steady flow of CO2, and reset it to that same flow when you have shut off the CO2 for some reason. Other than that it has no real significance.