Requirements and rules of soil device to aquarium
• The bottom layer should easily pass water, otherwise over time this can lead to the beginning of the decay process.
• No soluble substances should be released into water with a soil layer, otherwise it will inevitably affect the PH level, and some of the released compounds will simply poison all living things.
• There should be no mechanical danger to the inhabitants, especially fish that can get hurt about sharp particles.
Most often, sand or gravel (pebbles) is used to lover the bottom). Sand is not the best option, since it is waterproof, it forms many harmful compounds that can harm the inhabitants. The best option is gravel without sharp edges, with rounded grains size from 1 to 5 mm.
Gravel is washed with warm water in such a way as to clean it as much as possible from impurities of sand and clay. It is covered with a layer of no more than 7 cm. It is worth remembering that at first such an environment is lifeless. Saprophytic microorganisms that ensure the balance of microflora will appear a little later, so for starters you can mix to the base of a substance that can create a nutrient medium for plants.