The bases associated with alkalinity react with and neutralize acids.Carbonates and bicarbonates can react with both acids and bases and buffer (minimize) pH changes. The pH of well buffered
water normally fluctuates between 6.5 and 9. In waters with low alkalinity,pH can reach dangerously low (CO2 and carbonic acid from high respiration) or dangerously high (rapid photosynthesis) levels (Figure 2).