Organism particles larger than 5um would be certainly algae if they have symmetry and apparent organized structure. Planktonic protozoa rarely get dense enough to color the water, but it is possible. The water could have bacteria and algae in it, both contributing to the color. Sulphur odor is caused solely by the bacteria. They produce sulphur as a by-product of their anaerobic activity. The brown layer with odor directly next to the bottom will most likely be the result of anaerobic activity. It will contain no dissolved oxygen and can be verified by opening a bottle in this area/zone, allowing it to fill with water, capping it, then testing the water for dissolved oxygen.
What is the water temperature close to the bottom??
Others are correct, Bottom aeration sized, located, and operated properly will eliminate the sulphur smell and brown water layer that is next to the bottom. Bottom aeration if operated continuously will also make the water very similar temperature top to bottom all within 1-3 decrees C. Aeration may or may not make the overall water top to bottom clearer - higher visibility.
Last edited by Bill Cody; 01/27/16 11:59 AM.
