What is this brown stuff

[MarSch]

It's appeared slowly in the last 3 months and then spread rapidly in the last 4 weeks.

Dinos? Cyano? Chrysophytes? Something else?

There are lots of circles of it on my back glass as well.

Coralline seems to be spreading faster lately as well.

Fish all seem happy and healthy.

 

[EeyoreIsMySpiritAnimal]

Have you tried any manual removal? What are your parameters? What type of filtration do you use?

 

[shakacuz]

more hermit crabs or sand dwelling algae eaters like conches/cerith

seems like GHA, but can be another type. can’t tell when i zoom in

 

[Dan_P]

It's appeared slowly in the last 3 months and then spread rapidly in the last 4 weeks.

Dinos? Cyano? Chrysophytes? Something else?

There are lots of circles of it on my back glass as well.

Coralline seems to be spreading faster lately as well.

Fish all seem happy and healthy.

Imam of two minds on this one: GHA or Lyngbya. Can you post a clear picture of the growth on the glass?

 

[MarSch]

Imam of two minds on this one: GHA or Lyngbya. Can you post a clear picture of the growth on the glass?

Imam of two minds on this one: GHA or Lyngbya. Can you post a clear picture of the growth on the glass?

Sure, here you go

 

[EeyoreIsMySpiritAnimal]

Sure, here you go

Is that actually fuzzy? It looks like more coralline...

 

[MarSch]

Is that actually fuzzy? It looks like more coralline...

Doesn't look fuzzy on the glass but is filamentous on the sand

 

[Dan_P]

Sure, here you go

The organism on the glass, looks like it might be hard, seems different from the one in the sand, looks fuzzy

 

[MarSch]

Just for closure - thanks for the replies. On closer inspection it does indeed look like the glass stuff is different to the sand stuff.
I've vacuumed the sand stuff ut and kept lights low for a couple days and it does not seem to have returned (yet).
I've left the stuff on the glass alone