Sand Filter Backwashing
As dirt accumulates in the sand bed, resistance to flow increases, causing a reduction in water-flow to the pool or spa. When the flow is too low for proper circulation, it is necessary to clean or backwash, the filter.
To backwash a sand filter:
1. Turn OFF the main pump. (Never change the position of filter control valves with the pump running!)
2. Turn the control valve to BACKWASH position.
3. Turn the pump ON and allow it to run until the effluent water is clear, as seen through the sight glass on the backwash valve or waste piping. This takes 1-2 minutes.
4. Shut OFF the pump and turn the control valve to the RINSE position.
5. Turn the pump ON for 20-30 seconds. This resets the sand bed and sends any dirt residue into the waste line, rather than into the pool or spa.
6. Shut OFF the pump again, and return the valve to the FILTER position to resume normal filtering.
Diatomaceous Earth (DE) Filter backwashing
Diatomaceous earth (DE) is the fossilized remains of diatoms, a type of hard-shelled algae. DE filter cakes are made up of diatom fossils piled one on another to form a fine screen. The openings in the screen allow the flow of water but block even the smallest particles of debris.
Unlike a sand filter, where the filter media is cleaned and reused, the DE filter cake is discarded along with the dirt when the filter is backwashed.
The DE filter cake is held in place by a filter element (septum) made of a rigid grid structure, covered by a synthetic or metal fabric.
To backwash a DE filter
1. Empty the skimmer basket/s.
2. Turn the pump OFF.
3. Turn (figure #1) or pull (figure #2) the multi-port valve to BACKWASH.
4. Turn the pump ON and let it run until the effluent water is clear about 1-2 minutes. You can see the water in the sight glass on the backwash valve or waste pipe.
5. Stop and start the pump several times, to flush out maximum dirt.
6. Turn the pump OFF.
7. Set valve to filter (fig.1) or push (fig.2) the multi-port.
8. Turn the pump ON. Close the air-relief valve when water starts coming out of it regularly.
9. Check the water level and add more if needed.
10. Add 1 lbs. of new D.E. powder in the skimmer.
Pre-coating the filter media:
1. Read the directions on the DE bag carefully to see how much you need.
2. Be careful not to inhale DE
3. Turn the pump ON. Make sure the strainer basket is clean.
4. Using a measuring scoop, pour the required amount of DE slowly into to the skimmer.
5. Swirl the DE with your hand or a stick, to mix it with the water.
6. Keep the pump ON for at least 30 minutes.
Cartridge filters have a layer of layers of filter media made of pleated synthetic fabric attached to a cylindrical core. As water is pumped through the filter, it passes through the fabric, which traps debris. Like other filters, cartridge filters have inlet baffle system that keeps the water from hitting directly against the filter media.
To clean cartridge filter:
For pressure filters, be sure to shut the pump system off, close any appropriate shut-off valves, and open any air relief valves to allow air to escape before attempting to open the filter tank.
Remove the cartridges from the filter tank and use a garden hose to spray water at the pleats from a 45-degree angle. Hose the debris from between the pleats, being careful not to damage the bands. work from the top down in sections, and very back-and-forth motions with up-and-down motions.