Backwashing a pool with a cartridge filter system is a bit of a misconception because cartridge filters are not designed to be backwashed like sand or DE (diatomaceous earth) filters. However, cartridge filters do require regular cleaning to maintain their efficiency. Here's how you can clean a cartridge filter system:

 1.Turn Off the Filter System: Before starting the cleaning process, ensure that the pool's filter system is turned off to prevent any accidents or damage.

 2.Release Pressure: Locate the air release valve or bleeder on the filter tank and open it to release any pressure inside the tank.

 3.Drain the Tank: Open the filter drainage valve located at the bottom of the tank to drain out the water.

 4.Remove the Cartridge: Remove the top of the filter tank, which may require releasing a safety latch or lock. Once the top is removed, carefully take out the cartridge.

 5.Clean the Cartridge: Use a high-pressure hose to rinse the cartridge, removing any dirt or debris. Ensure that the water pressure is strong enough to dislodge any trapped particles.

 6.Inspect the Cartridge: Check the cartridge for any signs of damage such as tears or holes. If the cartridge is damaged, it will need to be replaced.

 7.Clean the Filter Housing: While the cartridge is being cleaned, also clean the inside of the filter housing with the hose to remove any remaining debris.

 8.Chemical Cleaning (if necessary): If the cartridge is heavily soiled or if you find yourself cleaning it frequently, it may require a chemical cleaning. Prepare a solution using trisodium phosphate (TSP) and water, and soak the cartridge overnight before rinsing it off with a hose.

 9.Reinstall the Cartridge: Once the cartridge is clean and dry, place it back into the filter housing, ensuring it is seated correctly.

 10.Replace the Top and Seal: Put the top back on the filter tank, making sure any gaskets or O-rings are in good condition and seated properly to prevent leaks.

 11.Close the Drainage Valve: Before turning the system back on, close the drainage valve.

 12.Turn On the Filter System: Finally, turn the filter system back on and check for any leaks or issues.

Remember that cartridge filters do not require backwashing in the traditional sense, and the cleaning process described above is to maintain their performance. Regular cleaning will depend on the usage and conditions of your pool, but it's generally recommended to clean the cartridge every few weeks or as needed.