Shallow lakes in Florida with lots of underwater plants were treated to control invasive plants. The treatments changed the water chemistry and the types of tiny organisms living in the lake. Less underwater plants led to more green stuff in the water and less diversity in the tiny organisms. There were more cyanobacteria when there were fewer plants. The treatments helped at first, but then the plants grew back, and there was a risk of too many cyanobacteria if the plants kept decreasing.