Acid Buffer™ is a non–phosphate buffer to lower pH and buffer with Alkaline Buffer™. Both buffers are designed for the planted aquarium or for very hard water where phosphate buffers may pose an algae or cloudiness problem. Acid Buffer™ lowers pH and buffers between 6.0 and 8.0 when used with Alkaline Buffer™. As Acid Buffer™ lowers pH it converts carbonate alkalinity (KH) into available CO2. What is the difference between Acid Buffer™ and Acid Regulator™ A: The difference is that Acid Buffer™ is a straight acid source and Acid Regulator™ is a phosphate based buffering system. Acid Regulator™ has a greater ability to maintain a pH as were a straight acid source can have a slight pH drift. When you are trying to avoid any additional phosphates I would go with the Acid Buffer™ and Alkaline Buffer® products but if that is not an issue, then the Acid Regulator™ will maintain a more constant pH.