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Optimal Timing and Proper Procedures for Replacing Filter Sand in the Sand Tank


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In swimming pools or water purification systems, due to the extended service life, dirt will continue to accumulate, affecting the filtration efficiency of the filter. One crucial question in daily maintenance is: how often should the sand be replaced, and how can it be replaced without causing damage to the sand cylinder? This article delves into this issue, providing in-depth research and specific suggestions.

The quartz sand in the swimming pool sand tank is best replaced every 1-2 years. The reasons for replacing the sand filter tank are as follows:

  1. Particle rupture caused by backwashing: Backwashing is a crucial step to ensure the normal operation of the sand filter tank. However, during backwashing, the volume of the filter layer increases by 1.2-1.3 times. The upward water flow causes violent impacts between the upper and lower layers of the filter layer, leading to the rupture of some filter materials into small particles, which are then carried away by the backwash water.
  2. Welding phenomenon of quartz sand: Some quartz sand may not be pure enough, and welding may occur when the pH value changes. This welding can impact the filtration performance of the quartz sand filter material and potentially damage the filter material structure, affecting the stable operation of the entire filtration system.
  3. Colloidal wrapping caused by uneven water flow: After long-term operation, the uneven distribution of water flow in the filter layer can lead to some filter materials being covered with gelatin, losing their original filtering effect. This increases resistance in the filter area, reducing overall filtration efficiency.

What are the correct steps to follow when changing sand?

Gather necessary tools and materials:

  • Screwdriver or wrench: Used to remove screws and bolts on the filter cylinder.
  • Pool filter sand: High-quality swimming pool sand is needed to fill the filter, and the quantity depends on the filter’s size.
  • Filter media alternatives (optional): Some pool owners prefer alternatives like vitreous or zeolite, which can enhance filtration and extend service life.
  • Watering hose: A hose with a sprinkler head is needed to clean different parts during replacement.
  • Plastic sheeting or tarp: Cover the area with plastic sheeting or a tarp to prevent leaks and debris from damaging the site during replacement.
  • Bucket or container: Used to collect remaining water during discharge.
  • Pipe sealing tape: If needed, apply pipe tape when installing threaded fittings to ensure a proper seal.

Turn off pool equipment: It is crucial to turn off the swimming pool properly before starting the sand replacement to ensure safety and avoid damage:

  • Find the switchboard controlling the pool pump’s power supply and turn it off.
  • Close all valves connected to the water pump/filtration system to prevent water flow into the filter.
  • If your swimming pool has a multi-way valve, set it to “off” or “antifreeze” to prevent water from entering the filter during replacement.
  • Finally, turn on or off the power supply of the water pump in the pool and turn off the water pump.

Remove old sand:

  • Use a small bucket or spoon to manually clean the sand in the filter tank, being careful not to damage the components inside.
  • If there is still a significant amount of sand left in the filter barrel after cleaning, use a wet-dry vacuum cleaner with a thin tube to suck away the remaining sand.
  • Use a high-pressure nozzle to connect the watering pipe and rinse all the remaining sand.

Add new sand:

  • Use a spoon or funnel to slowly pour the new sand into the filter tank, being careful not to disturb or move any internal components.
  • Fill to the recommended water level: Fill the sink with enough sand until it meets the sink manufacturer’s requirements or the standard water level specified for your specific filter model.
  • Use a straight edge (such as a piece of wood) across the top surface of the sand bed to ensure even distribution and a level bed height throughout the sand bed. Do not overcompact or compact the sand bed, as this will restrict water flow and reduce filtration efficiency.

Reassemble filter assembly: After adding new sand to the pool, the filter components must be reorganized, and the system tested to ensure that all functions are working properly:

  • First, put the branch pipe or vertical pipe back in the specified place and then place it at the bottom of the filter tank, making sure to hold them in place.
  • Replace other parts removed during cleaning or sand replacement, such as the diffuser, screen, or filter cartridge, carefully following the positioning and securing procedures specified by the pool manufacturer.
  • Before starting the test, carefully check the alignment and position of each component.

Test filtration system: After reassembly, it is important to test the newly filled filtration system to ensure its functionality:

  • Fill the pool with water according to the manufacturer’s instructions, typically involving injecting water into the pump until it drains away from any drain valve or vent.
  • Turn on the pool water pump, let it run for a few minutes, and check for leaks at the connections or seals of the water pump.
  • Pay attention to the water return port in the sink, checking its stability and continuity without abnormal noise or interference.
  • Check and monitor the pressure gauge on the filtration system when operating the filtration system under normal conditions. If you notice significant pressure fluctuations, this may indicate problematic filtration efficiency or blockage.
  • Backwash if necessary: If the pressure begins to rise after starting, follow the appropriate steps provided by the sink manufacturer for a backwash cycle.

For the replacement of sand material in the sand filter tank, it is crucial to choose the appropriate time and procedure. Determine when to replace the sand and adopt scientific and reasonable replacement measures to ensure the stable operation of the water treatment system and the clarification of water quality. Through the above suggestions, effective management of the sand filter, improvement of the filter tank’s operating efficiency, and the creation of a safe and healthy water environment can be achieved.

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