What is this and how to get rid of?

[partydiver]

After almost winning my battle with numerous types of algae. Ive noticed these green patches on the sand. I'm thinking its some type of green cyano. Its super dark green and only on the sand.
All my params are all good, just did a 5 gallon water change yesterday, good movement, protein skimmer operating normal.......
Its only a 28 cube too. 
Just don't know why it showed up and why its getting worse...

Sorry for the bad pictures, you would think a new camera can take good pics...

Bottom right corner of pics has the most

 

[unibob]

I'm not exactly sure of the Id on the algae, but I know my 29 gallon cubes sand looked like it always had a layer of something on it until I got some of the burrowing snails(forget name) and a diamondback goby. He just turns over gravel and cleans. Awesome fish. Lids are advised.

 

[Reef Hero]

What about a sand sifting starfish? I added one to my display about a year ago and it seems to keep the sand bed very clean and white looking.

 

[partydiver]

Sand shifting seems like a good idea. I have 3 Nassarius Snails now and a hermit crab. I used to have  Margarita Snails and Cerith Snails but they seem to die or get killed by something...

 

[jones02]

diamond goby