The filter layer of the filter is designed to expand upwards during backwashing. The upward water flow will drive the filter material to roll up and down, causing the particles of the filter material to hit each other, and then scraping off the impurities attached to its surface. Therefore, the hardness is also the same. The filter material will be partially broken into smaller particles that will be lost with the backwash water, and the broken small particles will be partially heavier. They will not sediment to the bottom with the backwash water loss and will pass through the water collection pipe. Enter the swimming pool, so it is necessary to do the drainage action of washing.

   Generally speaking, the filter's forward washing action is much more important than the backwash, because the amount and time of the backwash may not be enough to completely peel off the impurities on the surface of the filter material in the filter. When the water flows down to filter Some of the impurities that are not completely peeled off will penetrate downwards. If you enter the swimming pool, a black sewage trail will appear, making the pool water temporarily turbid. Therefore, the normal washing action of the filter is unavoidable.

    On the other hand, because it is possible to inhale air during the filtration and collect it in the filter, which makes the internal pressure of the filter unstable, it is necessary to perform the exhaust function. Therefore, the quartz sand filter has a series of empirical operating values, that is, When the head loss reaches 0.5kg / cm, the backwashing measures are taken and the air is exhausted at the same time. The time varies by 3 to 10 minutes depending on the size of the filter unit, depending on the quality of the backwashing water, and 45 seconds during the forward washing The difference of ~ 2 minutes depends on the quality of the washing water.

     Action of Aikelang automatic sand cylinder control valve:

    1) Filter (FILTER): When the automatic valve is in this position, it will have general filtering and vacuuming functions. The water flows from the top to the bottom and passes through the filter layer to return to the swimming pool to complete the function of detaining pollution particles.

    2) Backwash (BACKWASH): Backwash the filter bucket. When the pressure index of the filter rises to 0.5 kg, turn off the water pump, the control valve will automatically turn to the backwash position, and start the pump for backwash until The discharged water flow is clean. Depending on the diameter of the filter barrel, about three minutes to five minutes can be backwashed. If it is not clean, the backwash time can be extended. The water flow flows from bottom to top, causing the sand layer to float and agitating the sand layer. , So that the contaminated particles are stripped and discharged out of the filter.

    3) Forward wash (rinse wash) (RINSE): After backwash, close the pump, the control valve will automatically turn to the forward wash position, start the pump to run for 1 to 3 minutes, this is to confirm the backwash, then clean the All the dirty water is discharged. To prevent the dirty water from flowing back into the pool, close the pump, turn the control valve to filter, and then open the pump to allow the filter to operate normally. The water flows from the top to the bottom through the sand filter.