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Backwashing Pool Filter Weekly is NOT a Thing!

Backwash Pool Filter.

Filters are designed to have water run through them in a certain direction. To clean two of the three types requires manipulating valves so that the water flows through the filter backward. This we call backwashing. If overdone, this could cause extra unneeded stress on the internal components of the filter. Backwash Pool Filter.

Backwashing Pool Filter

Look at it like this if you had parked your car headfirst into a parking space. When it was time for you to leave, after you start your vehicle, you would put the gear selector into reverse. Then you would back the automobile up just to the point you could put the vehicle into drive and head off. Why wouldn’t you drive backward all the way to your next stop? Just because something can go backward, it doesn’t mean we should overdo it; sometimes, this is an option, but only to be done as needed.

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Okay, so a cartridge filter doesn’t get backwashed. It has to be manually taken apart and sprayed down, sometimes with a cleaner, every time it needs to be cleaned. This does not spare us the wear and tear of the process. Did you know that the minute that cloth band around the center of the element should unadhere, it’s time to replace the cartridge? Did you know it’s only glued in place? Repeated cleanings with a high-pressure nozzle or regular hose pressure can cause this to fail quicker than intended.

Backwashing Pool Filter

The band around the center of the element helps to keep the pleats in place. This allows the full square footage of the surface area to be used for filtration. Once the band fails, the pleats on the cartridge’s side where the water enters the filter will spread apart and take the brunt of the water. This will reduce the available filtering area exponentially.

Tear the DE filter grid, replace it with new. Break a lateral in a sand filter, and you’ll be scooping hundreds of pounds of sand out through a hole the size of a frisbee to repair.

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Instead of scheduling cleanings for a specific time frame, utilize the tools the filter comes with. Every manufacturer of every make and model of swimming pool filter instructs the operator to clean backwash decisions based upon the gauge readings. This enables the user also to consider the flowrate. That is why all filters, even when clean, with different pump brands and horsepower with plumbing configurations specific to each pool, do not operate at the same pressure (psi).

Cartridge Filter.

  • 8 to 10 psi (pounds per square inch) above clean running pressure.
    • Disassemble and hose down with a pressure nozzle on a garden hose. If the pressure rises again 8 to 10 psi within 24 hours of cleaning, remove and soak elements in a cleaning solution such as TSP and water overnight. Clean cartridge thoroughly before reassembly. Should pressure rise 8 to 10 psi within 24 hours of cleaning a solution, replace the cartridge with a new.

Pressure side vertical grid DE (Diatomaceous earth) Filters.

  • 8 to 10 psi (pounds per square inch) above clean running pressure.
    • Shut power to pump off. Manipulate the valve to the backwash position. Turn the pump on and allow it to run for two minutes or until discharge water in the sight glass is clear. Manipulate valve back to run position. Mix one pound of diatomaceous earth for every ten square feet of filter area into a bucket filled with water and stir into a slurry. With the pump on, pour the DE mixture slowly into the skimmer with the pump running.
    • If the pressure rises again 8 to 10 psi within 24 hours of cleaning, disassemble the filter with the pump off and remove the grid assembly—clean excess diatomaceous earth from the filter tank. Dismantle grid assy and soak elements in a cleaning solution such as TSP and water overnight. Rinse grid assy thoroughly before reassembly. Should pressure rise 8 to 10 psi within 24 hours of cleaning in a solution, replace the elements with new.
Backwashing Pool Filter

Vacuum DE (Diatomaceous earth) Filters.

  • Greater than 8 inHg (inches of mercury) – vacuum gauge.
    • Manipulate valves to stop water flow from skimmers, gutters, and main drain into the surge pit. Adjust three-way valve immediately in front of (influent) and immediately after (effluent) to draw water from surge pit and discharge to waste—drain surge pit. As the top of the elements breaches the water’s surface in the pit, rinse them thoroughly with a hose and pressure (fireman’s) nozzle. Allow vac pump to completely drain tank while cleaning but ensure vac pump does not run dry in the process.
    • Precoat the vacuum DE filter tank before returning to regular operation following cleaning. Allow surge pit to fill with pool water by opening valves. Manipulate the valve on the discharge side of the pump to return water to the surge pit. Mix one pound of diatomaceous earth for every ten square feet of filter area into a bucket filled with water and stir into a slurry. With the pump running, circulating the water in the surge pit only, pour the DE surry slowly into the water in the pit. Return valves to the normal operating position.
    • If the vacuum gauge raises to above 8 inHg (inches of mercury) within 24 hours of cleaning, repeat the drain and clean process above. Before repeating precoat, with surge tank empty and all pumps off, mix a cleaning solution such as TSP into a bucket of water and use the mixture with a toilet brush to scrub and cleanse the systems grids thoroughly. Should pressure rise 8 to 10 psi within 24 hours of cleaning in a solution, replace the elements with new.
Backwashing Pool Filter

Sand Filter – one pressure gauge.

  • 8 to 10 psi (pounds per square inch) above clean running pressure.
    • Shut power to pump off. Manipulate the valve to the backwash position. Turn the pump on and allow it to run for two minutes or until discharge water in the sight glass is clear. Manipulate valve back to run position.
    • If the pressure rises again 8 to 10 psi within 24 hours of cleaning, you can try using a sand filter cleaner. Follow instructions on the product label.
    • Replace the sand in the filter every five to seven years. Ensure 20-grade silica sand for swimming pool sand filter use is used.
Discussing filters in class at CPO Class

Sand Filter – two pressure gauges.

  • 8 to 10 psi (pounds per square inch) pressure differential
    • Shut power to pump off. Manipulate the valve to the backwash position. Turn the pump on and allow it to run for two minutes or until discharge water in the sight glass is clear. Manipulate valve back to run position.
    • Replace the sand in the filter every five to seven years. Ensure 20-grade silica sand for swimming pool sand filter use is used.

IMPORTANT!

Never change a valves position or setting with the pump running

All filter media, except for a cartridge element, requires the use of respiratory protection when handling. See product SDS for recommended PPE (Personal Protective Equipment).

2 thoughts on “Backwashing Pool Filter Weekly is NOT a Thing!

  1. My pool 100,500 gal pool has 3 sand filters. Should these filters be backwashed separately or is it ok to backwash all 3 at the same time? Thank you for your help!

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