How many living things are in a drop of dirty water?

Corrections: Viruses are considered non-living organisms. They have DNA or RNA, replicate and evolve but do not have metabolism and are not made of cells. They rely on host cells to survive. Here is a great debate between two microbiologist on whether or not viruses are alive. microbiologyso...
Also, most drops have a volume of about 0.05 ml. This is about a 20th of the measurement in the video. I used that measurement since that is what I found in literature.
How many organisms are in a drop of water? In this video, I added grass into a beaker of water and left it alone. After a few days, I looked at what grew and put it under a microscope.
I use:
Camera - Nikon D3300
Microscopes -
Wards trinocular Microscope (not sure the model) - 40X, 100X, 400X, 1000X American Optical One - Ten microscope - 150X, 600X, 1500X
The magnification is shown in the bottom right hand corner of each shot.