Improve swimming pool water quality: forward washing and backwashing of quartz sand filter

In swimming pool water treatment technology, quartz sand filters play a vital role. These filters effectively remove suspended matter and impurities from the water by using quartz sand as the filter media. However, over time, quartz sand can accumulate impurities and therefore needs regular cleaning. Two common methods for cleaning quartz sand filters are forward washing and backwashing. Understanding the differences between these methods is critical to ensuring efficient operation of your filter. This article discusses the specific operation process of forward washing and explains why it is necessary.

Why should we clean the sand?

The process and effect of backwashing are as follows

During backwashing, water flows through the quartz sand from bottom to top. The filter layer area increases by 1.2-1.3 times. This upward water flow causes the quartz sand particles to move up and down, rubbing against each other and dislodging impurities from their surfaces. However, since the quartz sand particles are of the same texture, this process also breaks some into smaller particles. Some fine particles, due to their relative weight, are not expelled with the backwash water but settle at the bottom of the filter.

The necessity of regular washing

The primary purpose of forward washing is to remove these broken quartz sand particles that have settled at the bottom of the filter. If not removed, these tiny particles can flow into the swimming pool with the water, leaving black stains. This is known as the “alien phenomenon,” causing the swimming pool to quickly turn black. Therefore, regular washing is a crucial step to ensure clean and safe swimming pool water.

Comparison between forward washing and backwashing

Compared to backwashing, forward washing plays a more significant role, especially when water resources are limited or the backwashing volume and duration are insufficient. If backwashing is not thorough, impurities on the surface of the quartz sand may not be completely removed. During subsequent filtration, these remaining impurities can penetrate the filter layer, leading to water quality issues. Therefore, conducting an effective forward washing operation is crucial for maintaining the filtration effectiveness of the quartz sand filter and extending its lifespan.

How to perform forward washing operations correctly ?

  1. Close the filter to prevent water from flowing through it during cleaning.
  2. Open the drain valve and empty the water from the sand filter until no water remains.
  3. Remove or open the upper cover of the sand filter to access the sand layer.
  4. Use tools like shovels or rags to gently remove accumulated dirt and impurities on the sand layer’s surface.
  5. Use an appropriate tool, like a long-handled shovel or stirring stick, to gently stir the sand, helping to loosen and separate impurities.
  6. Rinse the sand with clean water using a hose or other suitable tool. Maintain an appropriate flow rate to avoid damaging the sand grain structure.
  7. While rinsing, open the drain valve to allow water with impurities to drain from the filter.
  8. If necessary, repeat the washing process until the drainage is clear. After cleaning, ensure the sand layer is smooth and undamaged, with no excessive density.

By using these two methods wisely, you can not only extend the life of the filter but also ensure the efficiency and stability of the water treatment process. Selecting appropriate cleaning methods and performing them regularly will significantly impact the operation of the entire water treatment system

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