If those lights are 6 inches above the top of the tank, you probably have high medium light intensity, with all 4 bulbs on, which should be a good light level. A further advantage of having the light raised above the tank is that the intensity near the top of the tank isn't nearly as high as it is when the lights sit right on top of the tank. Algae grow in response to light intensity, just as plants do, so keeping the light intensity no higher than necessary is always a good idea.
I think you need to work more on the CO2 system. It is very difficult to get uniform distribution of CO2 throughout the tank, and keep it uniform as the plants grow. That requires keeping the plant mass from increasing so much that the plants block the water circulation. As you get more plant mass, their consumption of CO2 goes up, requiring a still higher bubble rate. A drop checker is very useful for giving you peace of mind as you increase the bubble rate - unless the drop checker is green you are very unlikely to have enough CO2 to bother the fish. Once you get the bubble rate up to where the color is green, then you need to slowly, a little bit each day or two, raise the bubble rate, while watching the fish carefully so you don't stress them too much, and watching the plants looking for pearling from all of the plants. If you notice the fish clustering at the top of the tank, usually in a corner, or some fish laying on the substrate, or fish losing their color, you have too much CO2, so you can then reduce the bubble rate back to the previous setting. That will be the optimum bubble rate for a high light tank.
Of course, good tank and filter maintenance is important too. BBA, once started, can be very difficult to eliminate, so it pays to do all you can to avoid it ever starting.