How to Use Secchi Disk to Measure Visibility 

Hello, can i use secchi disk even if the water is just knee level?

「明確なメッセージ、明確な構造、理解しやすい、ありがとう」、

「あなたはビデオにもっと明るさを与えようとします、そうすればそれは素晴らしいでしょう」、

Hi. What happens when the disk is vissible until it reaches the lake floor? Is it the considered as the secchi depth?

Some segments in the video are stamped not adjacent to each other