Jar with planktonic algae would have to be in the dark for several days to a good week or more for all types of algae to die and drop out.
To perform a turbidy jar test, collect a sample of pond water in a clear glass or plastic jar. A larger jar of 1 quart or even a gallon is best. Allow the water to sit undisturbed for 24, 48 and 72 hours. Then collect another identical sized jar of pond water. Visually compare the water in both jars. If the first jar is significantly clearer than the second jar of water then when the water in the pond is undisturbed the suspended particles will settle to the bottom. If water in both jars are close to the same clarity then the suspended particles will not easily settle and you will have to use a water clarifier or you have an algae phytoplankton (bloom) and/or a bacteria bloom in the water.
Carp are likely the cause of the brown water in above picture. As few as 6-10 would easily cause that amount of turbidity.
Last edited by Bill Cody; 06/19/15 09:22 AM.
