Protozoa prey upon the growing population of bacteria and also require oxygen. CBOD is a measure of the quantity of oxygen used by these microorganisms in the aerobic oxidation of organic matter. Many of the physical, biological and chemical characteristics of surface water are dependent on temperature. Conductivity measures the electrical conductants in the water. This is an indication of the quantity of dissolved inorganic acids, bases and salts in the water.
Total phosphorus includes organic phosphorus and inorganic phosphate.
Organic phosphorus is a part of living plants and animals. It is attached to particulate organic matter composed of once-living plants and animals. Inorganic phosphates comprise the ions of bonded to soil particles and phosphates present in laundry detergents. This scarcity of phosphorus is attributed to its relationship with organic matter and soil particles. Because algae only require small amounts of phosphorus to live, excess phosphors causes extensive algal growth called algal blooms.