Turbidity tube (45 cm)

• Fill your transparency tube completely with water, being careful not to disturb the sediment too much at your location, as it may affect the accuracy of your measurement.
• Peer down the top of the tube (do not wear sunglasses and shade your view from bright lights). If you can clearly see the black-and-white disk, record 14 NTU as the turbidity measure.
• If you can’t see the bottom disk, pour out water a bit at a time, continuing to check down the tube’s top until you can see the disk.
• Once you find the ‘sweet spot’ where the Secchi disk lines are distinguishable, check the side of the tube for the measurement in NTU. The higher the measurement, the less clear the water is.
• Pour out the remaining water and rinse your tube in clean water when you return home.