Help Identify different colors on my rock

[Eric H]

I set up at this 55 gallon saltwater tank about five months ago. Are used live sand but life rock. My rock started out bright white. It now has an array of colors to include red, green, brown and some spots of turquoise that’s not really viewable in the picture. If any of you experienced guys out there can take a good look and let me know if everything looks normal or off I would appreciate it. My water parameters are all good with the exception of my nitrates reading 20 despite frequent water changes and two bags of Denitrate and my filtration system. I also add a cap full of microbacter each week. Thanks. Eric

 

[Lasse]

It looks very clean and good for me - the colours you see can be coralline algae - and that´s good IMO

Sincerely Lasse

 

[vetteguy53081]

Brown will be diatoms
Pink will be coraline
Red/slimy will be cyano bacteria
Green will be algae
Slimy brown will be dinoflagellates