Algae in sandbed

[edolan]

I am trying to id this algae. It has pretty much taken over the entire sandbed. Hard to tell from the pictures but most of the sand is brown in color as a result. I believe that it started as cyano but I think there is hair algae in there as well now. Also looking for advice on how to handle it. I was going to start running some gfo but I get zero nitrates with an API test and zero phosphates on a Salifert test. I have also been siphoning the sand but it seems to grow back fairly quickly.

 

[ndrwater]

That looks like it might be the starting of bryopsis

 

[edolan]

I thought bryopsis grew more fern like. This looks like individual hairs to me. Maybe not the best pic but the best I could do holding a jeweler's lens up to my tablet, trying to zoom in and focus.

 

[amazongb]

Looks like gha to me