In Nature Aquarium, the bottom part of the tank covered by soil or sand is called “substrate“. The base sand consisting only of sand/gravel (such as sea gravels) holds the aquatic plants and also purifies the water with the help of the beneficial bacteria colonizing the sand/gravel surface. On the other hand, the substrate used in Nature Aquarium helps propagation of beneficial bacteria for stabilizing of the ecosystem within the aquarium. At the same time, it also supplies the nutrients to the plants for their healthy growth. The contaminants such as waste of fishes and shrimps kept in Nature Aquarium will be broken down by the bacteria present within the substrate and as a result, the inorganic matters are generated and absorbed by the aquatic plants as nutrients. As can be seen from this, the promoting the growth of beneficial bacteria within the substrate for luxuriant growth of aquatic plants will ultimately lead to the stabilization of the entire aquarium. For this reason, Nature Aquarium attaches the highest importance to the substrate and thus various researches and innovations in relation to substrate have been carried out.

Another purpose of substrate is to produce a natural feel within the layout. While a carpet of foreground plant creates a natural ambience within the layout, the materials such as cosmetic sand or Aqua Gravel used for the substrate can add a natural touch to the aquascape. In nature, sand and gravels are seen together with clear stream and spring water. Therefore, the natural landscape where clear water is present can be expressed by using sand and gravels as a part of the substrate materials.

Furthermore, long-term maintenance of the substrate is another important purpose in Nature Aquarium. When making a layout to be enjoyed just for a relatively short period (a few months to about one year), there is no need to make a highly elaborate substrate. However if the layout is to be maintained for a long time, how to build the substrate will be of great significance. Over the long time periods, the substrate is most likely to face the problems including compression of the substrate due to hydraulic pressure, poorer water circulation within the substrate due to such a compression and decrease in aerobic bacteria, which will  eventually lead to weakened aquatic plants and deteriorated aquarium water. In view of this, various substrate materials should be used in combination with the aim of creating a substrate suitable for long-term maintenance.