setup questions and algae

[linuxpng]

I have a reef tank (no sump) that's been set up for about 2.5 years now. Recently, I've started getting real bad algae problems. First a minor battle with hair algae that seems to be gone. I've started now with cyano. I've also really noticed that some of the coraline is starting to die off on my live rock (not much, but enough to concern me.) I have two inhabitants, a small yellow tang, and a clown fish (percula). There are a handful of corals and a clam in the tank that are all doing well, however. My water parameters are as follows... Salinity 1.026, calcium 400, Alk between 8 and 9 (low I know), undetectable phosphates, nitrate, nitrite and ammonia. In addition to the cyano, I seem to have a green algae growing on the back glass that is fairly persistant. It's not hair, but it's hard to scrape off. I use a maxima ro/di for water. Any ideas on what I could be doing wrong?

 

[NMreefer]

What about your lights?

 

[Ben1]

Also what size is the tank?

It is just a nutrient export problem. You may get an undetectable P02 reading but that is probably becuase your cyno is pulling it as fast as it is going into the water. You need to find a way to export more then you import. How often do you feed, what and how much?