Here are some pics before and after cleaning of the screen from my 55gal. ATS.
Also, I found an old microscope and decided to try and see if I could spot any pods from my screen. I took a sample of water with a spoon and put a drop on the slide. Just in one drop there were thousands. Lots of tiny dust size, and larger ones that dart across the slide and others just spinning around. Pretty fascinating to watch !!!