What is this?

[pochitafish]

Was doing a water change and after everything was said and done and was admiring my work, I noticed this pink looking stuff bellow my sand bed, is this Cyano?

 

[P-Dub]

If I were a betting person, that's exactly what it looks like to me.

 

[DexterKarin]

I have always had reddish substance under sand which is exposed to light against glass. Has never done anything but exist there. Never caused me any trouble.

 

[P-Dub]

If I were a betting person, that's exactly what it looks like to me.

And I should have added, it shouldn't be an issue, as most people and I have or have had similar microbial growth in the sand bed to varying degrees. I eliminated it by eliminating my deep sand bed. I go bare bottom now because I prefer sps dominance in my tanks and have so much flow that I would get sand blown out in areas anyhow.