Algae Happen: They are everywhere, but there is no reason to panic

If you are like most people who have just set up a new aquarium, the pristine tank—even without the first fish—fills your soul with unadulterated joy. you are exercising Zen patience and letting things run for a few days, and you can hardly wait to bring it to life. Then you realize it’s already alive! You see that first spot of green or brown, or possibly an attractive golden glow, edging out from the “sterile” base rock. What the hell is that? You haven’t added anything to the tank. Life has arrived on its own—but where did it come from?