Water transparency determination in lakes and oceans acc. to ISO 7027

ABOUT

The Visibility Disc acc. to Secchi is a white lacquered brass disk with a diameter of 200 mm and a weight of 1.7 kg. It is an easy-to-use instrument for stan-dard monitoring of water transparency in lakes and oceans. The standard Visibility Disc is equipped with a rope of 3 meters in length. The first 2 meters of rope above the disc have 10 marks every 20 cm for measurement purpose. For even more accurate readings we offer the disc with a 10 m long tape measure. The Visibility Disc is lowered into the water and the immersion depth is read from the marked rope or the graduation at the tape measure at the moment the disc vanishes from sight. It is lowered another 0.5 m and then heaved slowly again. The second reading is made when the disc reappears. The arithmetic mean from both readings equals the visibility depth.