What kind of grow bed is it that you can see to the bottom?
If a media bed that you just haven't put any media in yet, add the media and no worries you won't be able to see the algae anymore, it will die in there and help suppress further algae.
If a raft bed, put the rafts on to block the light and all will be good.
Surface algae is generally not to be worried about, it is only when the water gets so green you can't see the bottom that it is usually a bit problem, shade the fish tank to keep most light out of the water and you should be good there.
I don't recommend trying to clean algae out as it usually causes more issues than you solve. If it is actually gunk or string algae building up you can simply grab it by the hand fulls and put it in the compost.