I have always been fascinated by planted aquariums, wrongly called Dutch, in my opinion, and the benefits of plants for fish and the ecosystem as a whole. Browsing the Internet I found an article by another colleague with the same concerns as me, but which goes further by eliminating mechanical filters and replacing them with indoor plants. Here is the translated article: Ecology of the Planted Aquarium written by Diana Walstad is one of the books that inspired me the most to create natural, low-tech aquariums (Bio Aquarium, without filter, heaters,…). Diana Walstad explains why emergent plants are better water purifiers than submerged aquatic plants (in chapter 9, the aerial advantage). Compared to fully submerged plants, emergent plants are characterized by: Much faster growth. More efficient use of CO2 and light, (Ambient CO2 is not limited like dissolved CO2 in water.) More efficient oxygenation in the root zone. Emergent plants that receive natural sunlight can purify water much better than the best filter on the market. The faster a plant grows, the faster the water is purified. Having emergent plants for water purification is almost mandatory for keeping sensitive fish, such as Apistogramma species. Filters and water changes can thus almost be replaced by the services provided by these plants. Indoor plants most often used for water purification in aquariums. In addition to amphibious plants (Anubias and Echinodorus) I use a number of common indoor plants in my aquariums for water purification. That is, for the reduction of all types of organic and inorganic contamination; such as ammonium, nitrite, nitrate, phosphate, etc. In aquariums or ponds, fast-growing indoor plants (suitable for hydroculture) can be used. Emergent plants, or plants with the aerial advantage, are all types of plants whose leaves are not submerged in water. These can be land plants, amphibious plants such as Anubias and Echinodorus species, floating plants such as duckweed and water hyacinth, water plants with emergent leaves such as water lilies and lotus. Pothos (Epipremnum pinnatum, syn. Scindapsus aureus) Umbrella plants (Cyperus alternifolius) Ficus (Ficus pumila) Adam's rib (Monstera deliciosa) Bamboo (Dracaena sanderiana) Syngonium (Syngonium) I have had the best results with pothos. It is robust, adaptable and grows quickly. Its dense roots give a very natural and decorative appearance in an aquarium; they provide hiding places for shrimp and fry. It reproduces easily by cuttings, just cut some side shoots and put them in a vase with water. The roots will appear in a few weeks. At that time is when we should place it in the aquarium, attached to one of the side windows. Ficus is also a robust and adaptable species, but it is slow growing like Anubias. It can take years to grow, but once grown, it is a very decorative plant and a perfect water purifier. Over time it can cover the wall above the aquarium, looking very decorative. Umbrella plant is an excellent plant for large aquariums and ponds. Under natural sunlight it can grow up to 1.5 meters in height. It can be planted directly into the bottom substrate as long as the water depth is less than 40 cm. It is a robust and fast growing species. Being a fast growing plant, it keeps the bottom substrate healthy through its root network. It is perfect for purifying water in Lake Malawi and Tanganyika aquariums, as it can easily adapt to the high pH of the water. Adam's Rib is one of the best water purifiers, but it needs plenty of room to grow. I have tried all the plants in the list above except for Adam's Rib, with good results.