PHINFO

Taken from CT Project Search:

whether the water is acidic or "basic" (alkaline). It is measured using an electrical probe sensitive to hydrogen ion activity. The pH scale ranges from 1 (very acidic) to 14 (very alkaline or "basic") and is logarithmic. Thus, a change of one pH unit represents a tenfold change in hydrogen ion concentration. For example, a pH of 6.0 has ten times the hydrogen ions of pH 7.0 and one hundred times the hydrogen ions of pH 8.0. Because of this, it is inappropriate to calculate a mean pH. Rather, a median pH should be expressed.
 * pH:** pH is a measure of the hydrogen ion concentration of water, which determines

The pH of most natural waters ranges from 6.5 to 8.5. Deviation from the neutral 7.0 is largely the result of the interaction between acids and bases. Industrial and community wastes, acid rain, bedrock type, and the biological processes of photosynthesis, respiration, and decomposition all influence pH levels.

The pH of water is extremely important to aquatic life. Most aquatic species tolerate a limited pH range and most fish require a pH above 5.5 for growth and reproduction. If waters become too acidic, metals, such as aluminum and lead, can be leached from the surrounding soil and bottom sediments, contaminating fish and other aquatic organisms.

pH was tested by using an indicator that showed a yellow color if the water was acidic or a blue color if it was basic.