It looks to me like you could add more time, go to 20 hours. As long as you have the bioload to support continued increases, alternate between adding hours and increasing intensity. For the intensity, depending on how much you harvest, you can dial back the intensity to 3 for a few days right after a harvest. I will do this when I let the screen go too long and almost all the algae comes off without even trying - I'll dial back to 3 and 2-3 days later go back to max