I've had my BioCube 14 going for about 5 weeks. Last week I started to notice this brown stuff growing on my sand bed and on my rocks.

During the cycling of my tank, my phosphates hit 4 ppm, so I added some PhosBan in a micron bag to the back Sump area. (Last I checked, it was down to 0.6ppm)

At first I thought the brown stuff was the ferrous oxide (rust) from the PhosBan leaking into the tank. But when I changed the water and tried to siphon this stuff up, it was kind of sticky, and would come off in sheets, sort of.

I'm wondering, is this cyano? Here's a picture, tell me what you think. And more importantly, will it go away, and if not, how can i get rid of it?

1749

Thanks for your help!

It looks like diatoms. They are a normal phase for your tank to go through. It will go away. Mine disappeared when we want away for the weekend and left the lights off. I don't know if the lack of light was the reason it went away or if it was just time. :)

I believe Carmie is right. Since your PO4 is already pretty low, you could try uing one of the aluminum bases PO4 removers. they suck up silicate (which fuels diatoms) if there isn't any PO4 to remove. They're the white phosphate media instead of the brown stuff. That being said, they should go away on their own eventualy.

Are you guys sure about diatoms? I thought that i already had a diatom bloom when i developed the brownish gray dusty grainy type covering on the rocks and sand.

Can't be sure without looking at them under a microscope, but it sure looks like diatoms to me.

It is possible to have two outbreaks. Most tanks i have set up for myself go threw a small one and then lead into a larger one around the 3rd to 4th week. Also its depending on what you added to tank and the water quality. I would have to agree with diatoms.

Alright, i trust you guys. I'll go with the diatoms. Hopefully they clear up soon. Thanks for your help!

Generally, the algae cycle if brown to red to green.....I'm sure its brown diatoms.

also looks like diatoms to me. just thought i would add my $.02 to make it unanimous.