FILTRATION MODE
During the filtration process, unfiltered water enters the AGF system via the inlet manifold and the filtered water exits the system to the field through the outlet manifold. During filtration, the inlet ports are open and the backflush ports are closed. Water flows from top to bottom, across the sand layer.

BACKFLUSH MODE
During backflush, once a pre-set pressure differential or pre-set time is reached, the controller will activate one solenoid (valve and tank) at a time to perform a backflush operation. The inlet port closes and the backflush port opens. This reverses the flow of water in the media filter. Clean water from the other filters now flows into the filter from the bottom through every mushroom with equal pressure, lifting the sand media and freeing the accumulated debris. The debris will be flushed out the top of the filter through the backflush valve into the backflush manifold and to a suitable location. Only one filter should backflush at a time. The water that is backflushing one filter will have passed through the other filter(s) and thus backflushing will be made with clean filtered water.

As debris builds up in the media filter, a pressure loss will develop across the filter. The dirtier the filter becomes, the greater the pressure loss. When the pressure loss reaches a critical limit, the filter is dirty and in need of a backflush. Backflush controllers will sense the pressure loss through hydraulic connections and command a backflush sequence to begin when necessary.

1. Remove the top cover and before adding any media to the filters, inspect the inside of the media filter tank to be certain there are no foreign objects in the tank.
2. Check the mushroom covers and connector pins to be sure they are all in place and secured straight.
3. If possible, fill the tank with water and check for leaks.
4. Fill the tank with the specified amount of sand. The level is indicated on a label that is affixed to the tank exterior. If no label is present, it is recommended to fill the tank to 6” or 7” below where the dome starts.

1. Close all the valves and verify that no pressure remains in the tanks.
2. Open the upper service cover.
3. Open the 3” plug on the lower cover and drain all the water and sand from the filter. Remove the lower cover for faster draining.
4. Carefully rinse the inside of the tank.
5. Check the inside underdrain.
6. Close the 3” plug and install the lower cover (make sure threads are free of sand).
7. Fill the tank with water.
8. Add the new sand.
9. Open all the backflush valves in sequence.

• Monthly recommendation: Open upper cover and check sand level. Add media if required.
• The sand media will need replacing every few years as the sands edges become rounded. Sharp edges are necessary for proper filtration.
• Add chlorine at least twice a year to control organic growth in the filter. Apply 5 to 20 ppm according to the following directions:
  1. At the end of every irrigation season, add chlorine to the water in the filter for 30 minutes and allow to set. Backflush for at least 2 minutes. Drain all the water from the filter, leaving it dry and close the inlet and outlet valves.
  2. At the beginning of the irrigation season, fill the filter with water and add chlorine. Let stand for 30 minutes. Backwash for 2 minutes and begin irrigation.

  NOTE: Additional chlorine applications will be necessary in some areas.

  CAUTION: Chlorine is dangerous. Exercise appropriate caution and observe all applicable government regulations. Contact a qualified chemical dealer for assistance.

• System Operation
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