Reddish Brown Sandbed

[PaigeTX]

I’m here to ask the age old question, what’s on my sandbed? The more forums and photos I look at the more confused I become about the next course of action. 
 

My sandbed has developed a reddish brown stringy something. It’s only on the sand and doesn’t disappear when lights are out. No bubbles that I can see.

 

If anything, I think I’ve been feeding too much and not too little. I feed every other day - flakes, mysis every other feeding, and weekly reef roids. But I’m worried to make it worse. Can anyone tell what this is by the photos? 

 

The tank is three months old. All corals seem happy. I started with dry rock and it has developed some green film algae. 

[Humblefish]

Looks like cyano. Have you gone through diatoms yet? That would be my other guess.

[PaigeTX]

11 hours ago, Humblefish said:

Looks like cyano. Have you gone through diatoms yet? That would be my other guess.

I haven’t gone through diatoms but I’m leaning towards cyano as well. From what I read diatoms are from silicate in the water and my RODI tds is 0 so unless it’s from my sand or rocks I don’t think there are any silicates. 
 

I’m going to increase the flow and feed every 3rd day to see if that improves things! 

[Humblefish]

Almost all new sand contains silicates and it leaches out into the water. Diatoms will feed off these silicates until they are all used up. Usually lasts a month or so; typically the first stage of the uglies or new tank syndrome.

[PaigeTX]

1 hour ago, Humblefish said:

Almost all new sand contains silicates and it leaches out into the water. Diatoms will feed off these silicates until they are all used up. Usually lasts a month or so; typically the first stage of the uglies or new tank syndrome.

That is helpful, thank you! Hopefully that's what it is and not cyano. I guess I'll find out in the next few weeks.