Brown Stuff?


New member
Hello all. My 75 reef is humming along pretty good but I am having an issue with a brownish substance that grows mostly on the glass. I don't think it's cyno or dinos as it really doesn't appear to be affected by photo period. It appears more like the stringy bacterial colonies that bloom when carbon dosing. However, I'm not carbon dosing and haven't for several months. It wipes off of the glass easily and floats around in kinda of a gooey mass until the overflow gets it. I don't have any HA or Red Slime except a little in the fuge. Nitrate < 2 ppm and Phosphate = 0 on Salifert kits.

I do have microbubbles in the tank right due to a return pump upgrade. I am wondering if the brown stuff is just organic film with air bubbles trapped in it. Beyond that guess, I'm at a loss for an answer or remedy. Anyone have any ideas?