Led Lights and distance from screen

[den2fish]

Dear Scrubber forum,

I have a freshwater aquarium with a horizontal flow scrubber using LED reds and 1 blue. I was wondering what the best distance from the screen is for the lights. Right now it is about 4 inches, but I have wondered if it needs to be closer. I just started it a few weeks ago. There is black growth with some green algae now growing just not real fast. What would you suggest?

Thanks

[SantaMonica]

Dark growth always means it needs more light. So at least, increase the light hours.

[den2fish]

Thanks. I appreciate all the help offered on this site!