Physical Filtration in Aquarium Water Treatment

A good water environment is the basis for fish survival, and the quality of water directly affects the survival, growth and development of fish and other aquatic organisms. Therefore, the water treatment of the water body is particularly important. The soundness of the water treatment system is directly related to the health of the aquarium's aquatic organisms and whether the tourist experience is good. The life-sustaining systems of various aquariums are very different, and can be summed up as nothing more than the following components: filtration system, sterilization system, temperature control system, lighting system, nitrification and denitrification system (especially inland aquarium) and automatic control system. This article mainly introduces the filtration system, which can be divided into physical filtration system, chemical filtration system and biochemical filtration system. This article mainly introduces the physical filtration system.
Physical filtration system
The filtering function is mainly to remove any excess substances in the water through various filtering devices, including bait, body, secretions, excrement, protein and toxic nitrogen salts.
In a large aquarium that uses a closed life-sustaining system, the proper configuration of various filtration systems is very important to the improvement of water quality and water clarity. Basically, a life-saving system includes three filtration methods: physical filtration System; chemical filter system and biological filter system.
Physical filtration system method
① Physical treatment method: The method of separating and recovering the insoluble suspended pollutants in wastewater through physical separation can be divided into gravity separation method, centrifugal separation method and sieve filtration method. The processing units belonging to the gravity separation method include sedimentation and floatation methods. Corresponding processing equipment includes sand settling tank, oil separator, air flotation tank and its supporting equipment, etc. Centrifugal separation methods include screening and retention methods, such as centrifugal separators and hydrocyclones. There are screening and screening units. The equipment includes grilles and screens, sand filters and microporous filters. The main function of the physical filtration system is to remove suspended solids in the water to purify the water quality.
Surface treatment
Place filter materials such as artificial sponge and fine mesh cloth at the initial end of the filter system. When the water flows through the filter material, the remaining large suspended particles such as bait and fish manure in the water are intercepted. The purpose of removing impurities can be achieved by cleaning or replacing the filter material in time.
Air Lifting The standard type used in aquariums three or forty years ago. There are small water holes in the pipe, and air is pumped at the bottom of the pipe, forcing a vacuum at the bottom of the tank (pool), so that the suspended matter in the water is sucked to the bottom of the sand layer, and finally discharged out of the tank by suction. This system is suitable for large, Medium and small aquariums (pools). It not only can effectively precipitate suspended solids, is easy to concentrate and decontaminate, but also can effectively increase the oxygen content in the water.
Gravity sand filter method
The principle of gravity sand filtration is that when water flows through a porous filter material, such as a sandstone layer and other filter media, the flowing water will be precipitated, adsorbed and chemically reacted on the surface and internal gaps of the filter layer due to the mechanical barrier effect on the surface of the filter layer. The process of filtering out the solid substances, bacteria and other microorganisms suspended in the water or undergoing chemical or biological changes, so that the chemical composition of the substances contained in the water is changed and purified. In the gravity sand filter method, physical changes, chemical changes and biological changes are included.
Physical changes mainly refer to mechanical barriers, precipitation, adsorption, etc. Mechanical barrier means that the filter material removes impurities in the water (the size of the impurities is larger than the pore size of the filter material). This process has nothing to do with the filtering speed. Settling means that the pores in the filter layer are similar to the pores in the small sedimentation tank, and particles smaller than the pores of the filter medium can settle in the inner layer of the filter medium. Adsorption refers to the tiny suspended solids, colloids and dissolved impurity molecules that are adsorbed on the surface of the filter material under the action of molecular weight and electrostatic attraction.
Chemical change refers to the process in which dissolved impurities undergo chemical changes, such as oxidation or decomposition, to become harmless or insoluble compounds.
Biological change refers to the process in which bacteria or other microorganisms in the filter media degrade organic matter into inorganic matter through biodegradation, so as to achieve the purpose of purifying water quality. This process of change also includes killing pathogens and pathogens.
Pressure sand filter
The pressure sand filtration method is mainly to pump water into a filter equipped with a filter material through external power (from a water pump). When the water passes through the filter material, the suspended matter remains in the filter material due to mechanical barrier and physical adsorption. The upper layer and the upper layer can be removed by backwashing. The filter has a large water flow and can achieve a very ideal water cleaning effect. The particulate matter in the water is directly blocked in the gaps between the sand layers. In the pressure filtration system, chemical filtration and biological filtration will be greatly weakened. This requires maintaining good water quality by improving maintenance (ie, enhancing the intensity and frequency of backwashing) and increasing the processing capacity of the protein skimmer.
Generally speaking, the area of ​​pressure filtration is much smaller than that of gravity filtration, so it is suitable to choose the pressure filtration method when the space is relatively tight. In a pressure filter, the surface 2.5cm is usually the place where the most dirt accumulates. If too much impurities accumulate, a negative pressure will be formed on the upper layer, resulting in excessive internal pressure. Over time, these surface sands will be Become solid, the water will not pass through. Therefore, the filter needs to be backwashed regularly to remove dirt in time and reduce the pressure of the filter.
The surface treatment method and the air lift method are physical coarse filtration, which can only remove large particles of waste in the water body; while the pressure filter filtration is a physical fine filtration. According to the relevant literature records, the particle size and particle density of the quartz sand should be selected reasonably , The pressure filter has a significant effect on the removal of suspended matter, and the removal rate is as high as 99.83%.

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