The 13th Shanghai International Water Treatment Exhibition

- Aug 31, 2020-

1. Prevent the growth and reproduction of algae

Algae are extremely tiny plants, with hundreds of different types. Algae can multiply rapidly in water. First, it consumes carbon dioxide dissolved in the water, leading to a rapid increase in pH. Then, as the dead algae consumes the oxygen in the water, the clear pool water will become a dead water altar within a day. Airborne spores, lawns, and soil scours will bring algae into the water body. This often happens after heavy rains, especially when the water temperature is high.

Usually when there is enough residual chlorine in the water, algae growth can be effectively inhibited. The special algaecide crystal copper sulfate is easily soluble in water, can inhibit the growth of algae, and make the water appear blue. It is worth mentioning that you should not bathe in the family swimming pool to avoid serious water pollution.


Swimming pool water test kits


2. Control bacterial and virus pollution

In order to control the pollution of harmful bacteria and viruses, disinfectants must be added reasonably in the pool water. For home users, the most commonly used disinfectants are bromine and its compounds, and chlorine and its compounds.

Bromine and chlorine can kill bacteria, viruses and algae, and can play an oxidizing effect. Elemental bromine is a reddish brown liquid at room temperature, and granular methyl compounds containing bromine and chlorine are used for swimming pool disinfection. This compound is added to the circulation system to decompose hypobromous acid and hypochlorous acid. The cost of bromine disinfection is higher than chlorine disinfection, but its applicable pH range is wider. Under soft water conditions, bromine should be used as a disinfectant, and its concentration should be maintained at 4-6 mg/L.

water quality test meter

Hypochlorous acid is the main disinfectant. Its mechanism of action is: ①Penetrate the cell wall of microorganisms and destroy the protein and enzyme system of microorganisms; ②Remove organic and inorganic pollutants in water through oxidation.

The source of hypochlorous acid is calcium hypochlorite or chlorine. Calcium hypochlorite is a granular substance formed by calcium hydroxide absorbing chlorine gas and is a stable compound. Calcium hypochlorite will release chlorine after being added to the water, so it can be used as a disinfectant for swimming pools. Adding calcium hypochlorite will increase the calcium ion concentration and pH in the water, which is beneficial for swimming pools using soft water. There should be sufficient chlorination to keep the residual chlorine in the pool water at 0.4-0.6 mg/L.

When the concentration of organics in the pool water is high, a mixture of NH2Cl, NHCl2 and NCl3 will appear. This is caused by the reaction of chlorine molecules with nitrogen compounds in the pool water. This will lose the disinfection effect, especially NCl3 will make the pool water emit an unpleasant smell. Only by further increasing the chlorine dosage, can the NCl3 be decomposed. At this time, the chlorine concentration in the water will no longer continue to rise, and will continue to rise only after the NCl3 is decomposed.

water quality test meter

When the swimming pool has not been replenished with enough fresh water for a period of time, the content of Cyanuric Acid in the water is too high, and the phenomenon of chlorine lock-up will occur. That is, the chlorine is mainly treated by 2 swimming pool water or 3 chlorine molecules. The form exists, thus losing its disinfection effect. It has not been determined at what concentration cyanuric acid will happen. It is generally believed that the lock-in effect of chlorine is most obvious when its concentration is about 160 mg/L. After chlorine lock in the pool water, increasing the chlorine dosage can alleviate the situation, but the long-term solution is to add more fresh water.

On the other hand, cyanuric acid can act as a chlorine stabilizer. It is advantageous to maintain a low concentration in the water to prevent the ultraviolet rays in the sun from consuming residual chlorine in the water. It is usually added to the water in the form of particulate matter, and can also be produced during the process of dissolving the dichlorine complex or the trichlorine complex into the water: the chlorine complex** is a single chlorine molecule,

water test

At the same time, cyanuric acid is produced. Therefore, if a chlorine complex is added to the pool, the pool purification equipment does not need to add additional chlorine stabilizers. However, when sodium hypochlorite or calcium hypochlorite is used as a disinfectant, it is necessary to add a chlorine stabilizer. Care should be taken to avoid mixing the above-mentioned substances in a dry state, which may be dangerous.

Under special circumstances, an excessive amount of sodium hypochlorite or calcium hypochlorite can be added to the pool water at one time to form a higher chlorine concentration, inhibit the growth of algae and reduce the unpleasant chloroform odor, and can also destroy the gathered organic pollution Things. In addition, one-time excess chlorine gas is introduced to make the chlorine concentration in the pool water reach about 10 mg/L, which can have swimming pool water treatment effect to prevent bacteria and algae from multiplying. Family swimming pools can do this treatment once a week.