That of water lentils is a good system of natural phytodepuration, although it is not suitable for small applications or aquariums.
The water lentils on the other hand, they are interesting when the goal is the phyto-purification of tanks or basins of small residential settlements, agritourisms, farms or tourist villages.
There duckweed it is none other than Lemma minor, an aquatic plant widespread all over the world in different species that have also adapted to different climates. Its characteristic is to reproduce by splitting at a remarkable speed to form a waving carpet on the surface of the water.
The carpet formed by the Lemma, which to the eye resembles an expanse of lentils, has the particularity of absorbing large quantities of eutrophicating substances, but also of filtering light by stopping photosynthesis. This stops the development of other pest plant species.
The result is that, while the surface of the water is hyperoxygenated, an oxygen deficiency is created on the bottom which causes rapid anaerobic organic decomposition. The simple molecules that form on the bottom (ammonia, hydrogen sulphide, methane, etc.) rise to the surface where they meet oxygen which, oxidizing them, prevents the formation of miasmas.
The different combined actions of water lentils in practice trigger an effective reaction to contrast thewater pollution because, without causing bad odors, they quickly eliminate organic materials and nutrients. In this way they lay the foundations for a purification process that can continue up to water purification.
The main contraindication, as we said, depends on the size of the reservoir. There constructed wetlands with water lentils it is not really suitable for aquariums because it would cause a rapid colonization of space (Lemma minor reproduces very quickly), but it can be the right solution for reservoirs or water courses, and as an initial treatment of agro-industrial wastewater or as a first treatment large purification plants.
Duckweed is onealien plant.