okay so ive been out of the salt water game for about a year and a half, and my cousin has a bio cube that he doesnt want and is going to give to me! so i went over there and he totally let this thing go! he took the rock out and this is what it looks like! I know he should have the yellow tang in there! so that will be taken out but im worried about the algae in it. what do i need to do to get rid of it and prevent it??