The reason why Bio-Spira is much more effective is because it is cultured bacteria that is kept at a constant temp in a gel, where as cycle and stress zyme contains mostly dead bacteria because it isnt optimal temps for them. I am guessing since Bio-Spira, is kept cold, the metabolic rate of the bacteria is slowed down so the baceria don't starve. In the off the shelf bottles, the temperature varies significanly (almost freezing to over 100 depending on when it was shipped) and the aerobic bacteria get starved or sufficate from lack of oxygen. atleast that is how normal bacteria preservation is. keep it cold and slow down metabolism. heat it up and kill it. Come on, we all know about meats! Keep it cold til you want to eat it and then cook it so u dont get sick. Same goes for bacteria, except keep it cool so it doesn't die but not too cold.