Puzzled by red stuff reacting to different light

[jjencek]

I got what I thought was dino (or maybe cyano) appearing on the white sand everyday.

What puzzles me is the way it comes and goes. After a night the sand is perfectly white. The red will quickly show as soon as the daylight (not sunlight) hits the room. That does not surprise me, but ...

When my two Radions turn on at 11:00 the red stuff slowly goes away - two thirds of it is gone before lights out. I am using the "Coral Lab SPS AB+" setting at 75%.

Is it normal that this stuff does not like darkness and my Radions? What is the red stuff?

 

[mcgyvr]

Pictures?
Please take them with the blue channels way down or off to improve color rendition..

 

[jjencek]

Here is the picture. I think it is cyano, but the light sensitivity is throwing me off.