Please help. Dino’s? Diatoms? Cyano?

[Mr. Experience]

Hello, I have a new tank that’s been running for almost 3 months and a few days ago I started noticing my rock, sand, and glass have started turning brown. My tank has been cycled since week 2 so I don’t think it’s diatoms. I had something like this when I started a tank a few years ago and dinoflagellates ended up taking over my tank and I’m hoping that’s not what I’m dealing with again. It looks kinda patchy on the glass. Please help if it looks familiar to something you have/had.

Parameters:
Ammonia: 0
Phosphate: 0
Nitrite: 0
Nitrate: 10
pH: 8.0
dKH: 12

 

[KJ]

Diatoms.