Yellow Green Reef Rock

[carter92]

Any help with the cause of my Yellow Green rock in my 225 gallon Reef...Tank set up for 6months...I have tried everthing from carbon, light changes..more actinics....The left side of the tank is more obvious than right side...make me think that it might be a lighting problem...PVC which is pure white rules out yellowing of water....I know it will colonize with coralline over time, but the effect are very noticeable....I will attache some picture to illustrate...Thanks in advance......Dennis