1. Gently stir the sample using a moderate agitator. Before pouring the sample into the cell, wait for the air bubbles to disappear.
2. Fill the cell with a well-mixed sample and place it in an ultrasonic bath for 1 to 2 seconds to remove all bubbles, or use vacuum degassing to eliminate all bubbles. The turbidity of the water can be determined directly from the instrument display.
3. Calibrate continuous turbidity monitors for low turbidities using a laboratory-model nephelometer by determining the turbidity of the water flowing out of them.
4. Alternatively, calibrate the instruments using a formazin primary standard or a suitable secondary standard, as directed by the manufacturer.