Seaweed growing

First I am new to the world of aquariums and reef tanks. We have started a 65 gallon tank and put in about 60# of live rock. 1st week added a melanurus wrasse and second week 2 clownfish. Heres what I am am questioning. There appears to be a lot of seaweed growing from the live rock. It starts very clear and skinny the first couple weeks. Now this is the beginning of the 3rd week and it seems to be getting thicker and more abundant. Is this normal and is there a way to control it. Have posted a picture of it.