This marine aquarium is going down the drain. Literally. Just look at the amount of green algae covering the rocks and it is not hard to estimate the amount of nitrates and phosphates present in the water. I bet the poor soft leather coral and the once beautiful but now sparse looking Xenia are suffering, and it is just a matter of time before they die out.
I love marine aquariums very much but when I see them in this state, I do feel sorry for the living organisms in the tank.