I am using this DFRobot Turbidity sensor. The associated wiki page has some sample code that includes some sample code and some information about converting between voltage and NTU (Nephelometric Turbidity Unit)
But I would like to verify this relationship and explore how various factors effect its accuracy. To do that, I would like to have some way to calibrate these sensors.
It appears that distilled water should have a turbidity of less than .1 NTU. It appears that you can purchase Formazin solution for turbidity calibration that comes in a standard 4,000 NTU solution.
Instructions that I have found on the internet say that you take this solution and "dilute it to the desired instrument range."
Is turbidity going to decrease linearly as I dilute this solution? So if I make a preparation of 1 part Formazin solution and 1 part distilled water, should it have a turbidity of 2,000 NTU?
Is this a good way to go about this calibration and testing? Are there other techniques I should look at?