green patches on the sand bed

[David Cher]

hi folks i am getting like green patches on my sand bed , is that normal it is clumping my sand together

 

[KrisReef]

Clumping sand sounds like high alkalinity or really low pH.

I can’t remember if cyano comes in green, ( I can’t believe I typed that) or maybe Cyanobacteria carpet sticking to the substrate?

 

[Subsea]

Would you take a picture under white light. I can’t see green with the blue light.