Hmm, I like the white disk idea. I will try that. I dialed the reds way back, which I needed to do anyway, so the funky red shimmer is not so bad, but I still want to improve it. I am still tweaking the color. Looks like the whites need to come down a little as well. Problem 1: the PWM response is totally not linear. So cutting PWM rate in half reduces light by much more than half. Problem 2: Nothing useful in the tank. All I have is white rock, white sand, and brown algae. Need some paint samples or something.