How much space is between your light and the water level? I use a current t5HO with 2 bulbs and with just the legs seperating it between the water line (around 4-5") I would get BBA on the plants closer to the surface. The reflectors on this light are pretty good. Increasing CO2 was not an option due to high KH/GH so I used photo nuetral density paper to reduce the light by about 30%. Window screen works too. Also, with that light close to the surface you probably need better CO2. Use a drop checker to see where you are at.