Quartz sand filter plays a key role in the water treatment system. It can filter out impurities and particulate matter in the water and ensure that the quality of our swimming pool water reaches standards. However, many people have questions about the maintenance cycle of quartz sand filters, especially the backwash interval. How often should quartz sand filters be backwashed? This not only involves the life and performance of the equipment but is also directly related to the water quality and safety of our swimming pools.
Ⅰ. What is the frequency of backwashing?
When the filter media layer is in normal use, pollutants on its surface and within the layer will be intercepted and adsorbed, causing the pores of the filter media layer to become thinner or blocked. This results in the water pressure loss flowing through the filter media layer gradually increasing, and the water output decreasing, making it unable to meet the requirements of circulating water. To ensure the filter works normally, the filter medium inside the filter must be cleaned. During this process, various pollutants adsorbed on the surface and within the filter media layer are removed through backwashing to restore the filter’s filtration capacity. Therefore, the time period from when the filter starts filtering water to when the outlet water quality cannot meet the requirements and backwashing is required is called the backwash frequency.
Ⅱ.Situations when backwashing should be carried out
1、The difference between the inlet water pressure and the outlet water pressure reaches the specified value or 0.06MPa.
When the difference between the inlet pressure and the outlet pressure of the particle pressure filter reaches 0.06MPa specified by the supplier, or reaches the difference specified by the equipment.
Reason: This may indicate that the filter media layer has been greatly contaminated, resulting in a decrease in filtration efficiency, and backwashing is required to remove contaminants.
2、Continuous operation for more than 5 days but the difference does not reach the specified value.
When the particle pressure filter is operated continuously for more than 5 days, even if the pressure difference between the water inlet and the water outlet does not reach the specified value of 0.06MPa.
Reason: Although the difference does not reach the specified value, long-term operation may cause the contaminants intercepted by the filter media layer to solidify, and backwashing is required to prevent solidification and maintain filter performance.
3、Disablement occurs during operation.
During the operation of the pressure filter, although the pressure difference between the water inlet and the water outlet did not reach the specified value, the continuous operation time of 5 days was not reached due to some special reasons, such as the swimming pool being out of service.
Reason: Before deactivation, to prevent solidification of pollutants in the filter media layer and aging of the anti-corrosion layer, backwashing is required to maintain filter performance, avoid cracks or cracks, and ensure effective filtration after reactivation.
4、Planned or unplanned backwash before decommissioning.
Before the planned or unplanned decommissioning of swimming pools, amusement pools, leisure facility pools, and artistic performance pools, backwash the pressure filters used in the corresponding deactivated pools one by one, and drain all the water in the filters.
Reason: The purpose of this step is to ensure that the filter media layer is clean, prevent contaminants from solidifying, and the anti-corrosion layer from aging, and ensure that the filter remains in good condition during the outage so that it can effectively filter pool water when it is reactivated.
Ⅲ.What else should you pay attention to when performing backwashing?
1、When using pool water as a backwash water source
(1) Selection of backwash time period:
Backwashing should not be carried out during the public use period of swimming pools, amusement pools, etc., to ensure that the effective water depth of the pool water is not affected and the normal use of the pool water is ensured.
(2) Backwash timing for normally open swimming pools and amusement pools:
Backwashing of the filter should be performed after each session or daily open use. When there are multiple filters, it is advisable to select one filter for backwashing every session or every day to meet the requirements for the normal replenishment of new water in the swimming pool.
2、Use of the filter backwash pump
The filter backwash pump should be carried out using a pool water circulation pump. However, when using a circulating water pump, the working conditions of the circulating water pump should be checked based on the backwashing conditions of a single filter to ensure that the water pump can meet the backwashing requirements.
3、Backwash and drainage requirements
The backwash drainage should be ensured to be unobstructed, and a short transparent pipe for observing the clarity of the backwash water should be installed at an appropriate location. In addition, backwash drain pipes should not be directly connected to sewage and stormwater pipes to prevent cross-contamination.
4、Guarantee of backwash intensity
In order to ensure the intensity of backwashing, a flow metering device with an accuracy of no more than 3% should be installed on the backwash inlet pipe. This way, the flow rate of backwash water can be accurately measured during the operation of specific engineering equipment, thereby ensuring the effectiveness of backwash.
In practical applications, how to scientifically and reasonably select the number of filter backwash times is the key to ensuring the long-term stable and efficient operation of the device. We should fully understand factors such as water quality conditions, equipment specifications, and usage environment, and develop a reasonable maintenance plan. Through scientific management and maintenance, we can better ensure the stability of the quartz sand filter and thus better treat the swimming pool water quality.