Diatoms or Algae?

[JordanM]

This tank has been cycled for about 6-8 months now. Only difference is that I just added corals to it and started using the lights. This is when this brown substance started growing on the rocks. What are your thoughts on what it could be? All the corals are still looking good but the RBTAs are looking a little lighter in color. Ammonia, Nitrite and Nitrate are all 0. I do not have a way to test phosphate.

I do see some areas of green algae but not as much as the brown.

 

[sfin52]

You don't want nitrate at zero 5-10 ppm and you will want to get phosphate tested as well

 

[cloak]

Diatoms most likely.

https://www.reefcleaners.org/nuisance-algae-id-guide

 

[saltyfilmfolks]

Looks like a mix of stuff. Normal with new tanks, you just added lights.

Run an agressive carbon or purigen.
Some of those put off some stuff into the water other organisms don’t like.
Keep an eye on the Nem. It just might not like the way the water tastes right now.

 

[JordanM]

Thanks. My first thought is diatoms. When i wisp my hand over the rock the stuff goes blowing away very easily and only the green is left which im not too concerned about. I might get some GFO and carbon and add it to one of my canisters just in case. I also have the Red Sea algae control test kit for NO3 and PO4 but all the reagents are expired so I should probably reorder those.