green algae

Ok my tank is over a month old and I have had a light coating of brown
algae on the bottom for about three weeks now. I was told that it is
not harmful to my tank so I have not worried about it. On monday while
doing my regular tanks maintenance I noticed some green algae on the
sand and I am wondering if this is also ok for my tank? If not how do I
keep it under control without adding chemicals to the tank. In all my
years of fresh water tanks I have never had any noticeable algae
problems so this is new to me.
I have read that green algae is a good food source for many animals but
I don't have anything in there now that would eat it. I keep a few
damsels and I know that there are compatibility problems with adding new
fish and since I like them, don't want to get rid of them if I don't
have too.

Any suggestions would be helpful.
Thank you in advance.
Vicki