Calculating ppms

Biocide dosage levels are often prescribed in "parts per million"or "ppm." Logically, one part per million is represented as 1/1,000,000, 0r 0.000001. Here is a practical method for calculating ppm using the C1V1=C2V2 calculation. If you want to add 35 ppm of biocide (C1 = 35/1,000,000) to preserve 2,000 liters of material (V1 = 2,000), and the biocide is undiluted (C2 = 1.00) the calculation to find V2 (the volume of biocide required) is 2,000 liters x 35/1,000,000 = 0.07 liters of biocide, or 70 mls. If the biocide has already been diluted, which is often the case for lab studies, C2 will no longer be "1.00." For example, if your biocide has already been diluted 10% , then C2=0.10.