Acid Buffer is a nonphosphate buffer to lower pH and buffer withAlkaline 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.