FLOATING PLANTS
In addition to being prolific growers, floating plants also help to keep the water clean. Some are annuals, and should be thrown away in November. However, these plants are worth their weight in gold for their ability to provide shade for the surface of the water.  They feed from the minerals in the water and thus control algae which are responsible for turning the water green.

Container: None.
Soil type: None.
Fertilization: None.
Planting: They float on the surface of the water.
Quantity: At the beginning of the season, about one plant per m².