GREEN CYANO/ MYSTERY DETRITUS

8 months ago I began my nitrogen cycle in my 55 gallon tank. 6 months ago I added the first fish. The fuzzy dwarf lion died 2 months later while I was on vacation. In the time before I got the fish the tank became infested with green hair algae. By the time he died it was covered with green and purple cyano. I think the cyano came back because I was overfeeding him. Since he died I have gotten a small clown (pictured)

I know I am not overfeeding him, he gets a mysid a day. So I syphoned the cyano of only to discover the dead hair algae. (pictured)
The cyano once again begins to grow back. I read that that cyano is feed by high nitrates (mine are zero) over feeding and decaying organic matter. Would the dead hair algae be feuling this cyano infection?

The flow is 1280 gph and I my water is RO/DI.

Usually two pieces of a mysid. The shrimp I have doesn't come in cubes. I know where the phosphates are coming from, the dead algae. I have started to siphon it out. Is there a quicker way of getting it out?

With what and in what. Oh yes, and thank you for the help.

Thank you, I'l do that tomorrow.