Our tanks are always changing to reach a state of equilibrium.
There is obviously something fuelling the algae growth, and I know we have different opinions on this subject...so I hesitate in asking....
How old are your rocks? ..or..
Can there be any areas of detritus accumulation that have been sitting there for a while?
I'm not on the Biopellet bandwagon yet, but they may turn out to be yet another good form of nutrient export.
I am probably going to be hooking up a second skimmer fed by my 1st skimmer in my ongoing battle for nutrient export.
Just a suggestion anyways.
Mitch