hipower,
I think that's a good thing. That's what it's there for I thought. You would much rather have it growing there then invading and choking out the main system where all your prized corals are.
However, I run a pretty powerful led over mine and all I get is micro algae. Same as in my main tank. But I do have a established system. I have noted bubble algae in my overflow box and have left it there. Also, my Tunze wavebox as well. Even though my nitrates read zero, if I cut back on feeding my fish, micro algae slows considerably throughout the tank. But I like having fish with my SPS. I have 5 fish, and they are fed about 3 times a day almost everyday.
There has to be a balance to each system, or a balance YOU the aquarist must find or reach for your particular system. Just because you get a new piece of equipment does not mean its going to all be good. And a newly established system will have you pulling your hair out of your head chasing it and trying to fine tune it. I would say a established system could be anywhere from 12-24 months. Maybe sooner if your transplanting from another tank.
It takes me time to see whats going on in any tank..........