Additionally, i doubt that light puts out anywhere close to what the sun outputs. Our high light hits around 100-150 PAR, and the sun 2000. You need to give you plants time to grow, not expect perfection right away. It may take months, but be patient. Adjust CO2 in accordance to light intensity.
Plants can typically transition from higher light to lower light without an issue, but a jump up in the other direction is not tolerated as well. So once again, be patient, adjust light period if you can. I cannot understand why you refuse to turn your lights off sooner if you are concerned with too much light.