Question: What are different methods of measuring water turbidity?

@gilbert has compiled some more information on this over here: https://publiclab.org/notes/gilbert/09-22-2017/turbidity-mesurement-methods-regulations -- thanks!

I've noticed there are a couple different methods for monitoring turbidity:

• Secchi disks: where users putting a disk into a body of water and measuring the distance in the water until the disk is no longer visible.
• Turbidity tubes: which require a sample of water to be viewed by the naked eye through the tube, and
• Turbidity meters: which requires a sample of water put into a meter that measures the amount of scattered light that sample produces (when with a light is shown through a sample at 90 degrees).

I'm wondering, under what conditions would I choose between these different methods? Posted that question here.

Folks at NASA AREN (#aren) sent this over -- a smartphone method for water color, interesting!

http://misclab.umeoce.maine.edu/research/HydroColor.php

The prevalence of cell phones among teachers and students provides for the possibility of water quality monitoring with minimal financial investment (In contrast, the Hach turbidity meter used to calibrate HydroColor costs ~$1,000.00). The only investment required (assuming an iPhone is available) is a photographers gray card, which can be purchased for a few dollars.