Gravel and sand as aquarium soil.
Soil in an aquarium with plants is one of the most important components. It contains the roots of algae, and from it the plants receive the necessary nutrient minerals for their growth and development.
Usually the main component for the preparation of aquarium soil is fine gravel 2-5 mm in size. For plants, it does not constitute a source of nutrients and does not have the ability to retain them. It is mainly used to hold algae roots as the top layer. On the other hand, gravel allows nutrient minerals from water to easily enter, where they are absorbed by the roots of algae.
Fine sand is close to gravel in that it does not contain nutritious minerals and poorly holds them in itself. As a rule, it is used in a mixture with other types of soil, such as peat, or as the top layer. Fine sand should not be used in the presence of a bottom filter, since it is very quickly clogged with dirt and there is a risk of anoxic zones.