There are three main types of pool filters: Sand filters, cartridge filters, and diatomaceous earth filters1. Of the three, sand filters are probably the most trouble free. Cartridge filters are the easiest to maintain, and DE filters are arguably the most efficient. DE filters use a mined product as a filter media that coats a series of grids in the filter housing. Water is forced under pressure through the grids where the DE media traps particles as small as 3 microns. Cartridge filters remove 25 – 50 micron size particles from the pool water. They should be replaced every few years, not more than 5 years apart.
Maintaining a sand filter
- Check the filter gauge frequently. When the gauge pressure reads 8-10 pounds per square inch (psi) higher than it did right after the filter was last cleaned, it is time to clean it again.
- Shut off the pump motor.
- Move the multi-port valve handle to the backwash position to backwash the filter.
- Open the air bleed valve on the filter and the waste valve.
- Turn the pump on.
- Let the water run until it runs clear.
- Shut off the pump and move the valve handle to the Rinse position.
- Turn on the pump and rinse the filter for about 20 seconds.
- Shut off the pump again and move the handle to the Filter position.
- Turn the pump back on and write down the lower operating pressure.
Cleaning a DE filter
- Backwash a DE filter whenever the operating pressure rises about 10 psi above the normal filter pressure, which is that gauge reading right after backwashing the filter.
- Backwashing a DE filter is the same as for a sand filter except that you should perform the backwash operation several times in a row.
- Place the filter back in operation, then check and record the lower operating pressure.
- Add approximately 1 pound of diatomaceous earth to the pool skimmer for each 10 square feet of filter area. You can find the total filter area by checking the filter label or manufacturer’s instructions.
Cleaning a cartridge filter
- Shut off the pump.
- Open the air bleed valve on the filter housing.
- Once the system is de-pressurized, release the lid and remove it.
- Remove the filter element.
- Hose the element off starting at the top of the element and flushing the dirt and debris downward.
- Reinstall the cleaned element in the filter housing.
- Replace the lid.
- Close the air bleed valve.
- Restart the pump.
You can add a small amount of synthetic filter aid powder or a clarifier to the cartridge filter to increase efficiency.
Every 5-7 years replace the sand in the sand filter. Be sure to use sand specifically rated for use in pool sand filters.
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