What is the difference between and algae bloom in the water, and the stuff that grows on the sides of the tank? Are they one in the same or two different types. Also, what is the best way to deal with the kind that grows on the back of the tank? I have a blue background and now have spots that look black growing on it. I am assuming it is just algae growing and should just wipe it off during water change, but thought I would ask the experts.