green algae advise

[omoreno]

My tank has been up for about 8 months. I have good pink coralline aglae growing on the glass but I also have a green coralline algae growing on the glass. It is flaky and somewhat touch to scrap off the glass. What is the green algae? Is this normal for a tank of this age? Tank is a 55 gal. I do a 10% water change every 2 weeks.

Thanks.