Algae Control, Green Water Bloom.
This is an old video with good, current information. Crude in it’s cinematography, but full of good information. Greenwater is basically just that: Green Water which obscures your view of the fish, but is healthy. It is a product of nitrogen fuel, fish, sun and a failure to have competition from live plants. Chemistry is not the cure. You will do well with a pen and paper as the video presents a lot of information FAST.