The analysis is as follows:

1. There are two types of circulation systems that need to be established in separate fish tanks, one is the oxygen circulation system and the other is the nitrogen circulation system.

2. The process of the oxygen cycle system is as follows:

(1) Oxygen, animal and plant respiration, carbon dioxide, plant photosynthesis, oxygen.

(2) The formation of this cycle requires the participation of aquatic plants. If aquatic plants are not planted, it can be solved by using air pumps to increase oxygen.

3. The process of the nitrogen cycle system is as follows:

(1) Organic matter, decay, ammonia, nitrosation, nitrite, nitrification, nitrate, denitrification, nitrogen.

(2) Plants can also be involved during the operation and be directly absorbed. In addition, denitrification is generally only required for seawater tanks. 4. It is worth noting that the above cycle is only carried out partially in the small environment of the fish tank and does not form a complete closed loop. Additional additions, replacements and other intervention are required.

Extended information:

Water circulation system

Various water bodies on the earth pass through evaporation (including plant transpiration), water vapor transport, precipitation, infiltration, surface runoff and A series of processes and links such as groundwater runoff organically connect the atmosphere, hydrosphere, lithosphere and biosphere to form a huge "water circulation system".

Reference: Circulating water system_Baidu Encyclopedia