Black Light is a simulator of real black light. In the app you can change and select the TONE of color that you want (Deep purple variations), the TIME that you want the screen will be active and the BRIGHTNESS of your screen.

All the colors in "Black light" are optimized to show a powerful radiant effect in the dark

"Black light" is only for fun and doesn't produce real black light, "Black light" just mimics the color of a black light.