If it is bad you can have lights on less, feed less, get something to eat it, or do more water changes. Maybe a combo of everything.
It took me a while to admit I had a problem because I was good on light feeding and water changes, but once I realized something had to be done I dropped my lights down to 5 hours a day and got a pleco. Bye bye algae. I don't even have to clean the walls anymore.