What you need to know about the swimming pool filter?

Elvis Elvis

The Swimming Pool Filter needs a few moments of attention each week to stay in tip-top shape as well.

The part of the Pool Filter where the tiniest particles of dirt are removed is in the tank. This large tank is usually made of metal, concrete or fiberglass and is usually some sort of cylindrical shape.

Plenty of dirt collects in these filters over time and must be removed in order to maintain an efficiently running system. The flow of water slows down; the pressure gauges at the tank indicate the level of blockage inside.

-The Workings of the Swimming Pool Filter-

Lets start with a very general overview on how the swimming pool filter works.

The water is brought by way of the Pump through the swimming pool filter, either up the manual or automatic pool cleaner, through one of the main drains or skimmers. It is then filtered again through the strainer basket, which is removable for easy cleaning.

The twice-skimmed water flows in through the filter’s inlet pipe, which leads to the Water Distribution Head inside the tank.

While gravity pulls the water down through the sand filter, cartridge filter or DE Filter all the tiniest particles of dirt left will be filtered out at this point.

The clean, filtered water then flows back out into the pool.

What you need to know about the swimming pool filter?

-The Different Types of Swimming Pool Filters-

I’ll give you an overview of each type of swimming pool filter. This will help you when discussing the pool filter with your pool contractor or pool supplier in deciding, which is right for you and your pool.

-My Two Cents-

On our pool we have a DE filter. When properly maintained and flushed the DE swimming pool filter will give you the clearest water…”my opinion”. Sand filters work well, but the water is usually more cloudy than a DE or cartridge filter. Some claim that the newer cartridge filters will get your pool as clear as the DE filter and a small amount of DE can be added to the cartridge filter.


In the DE filter or diatomaceous earth filter, water from the pool passes through swimming pool filter grids coated with diatomaceous earth, a fine powder of diatoms or chemically inert, fossilized remains of sea organisms.

The gauges will indicate when to flush out this system. Usually when the psi rises 10 increments above where it started.

The procedure to flush the swimming pool filter varies slightly from different manufactures. The basics however, are similar.

First, shut the pool filter off and open the flush valve. Turn the pool filter on and let the water discharge for a couple minutes or until it starts to run clear. Then turn the pool filter off and close the valve. Turn the pool filter back on and let it run for a couple minutes.

Repeat these steps a few times until the water runs clearer and the pressure is back to your normal starting point.

After flushing the pool filter you will need to add some DE back into the system. The pool filter manual will explain this in detail.

When flushing the pool filter doesn’t reduce the pressure then it is time to clean the filter grids. This needs to be done 2-3 times a year.

To do this, remove the tank housing, take apart the filter grids (puzzle), which is coated with the DE, and rinse it all down with a hose.

Assemble it as before (puzzle?…you’ll understand now), and turn the tank on. Depending on the size of your pool filter, replace the recommended amount of DE into the skimmer basket while the system is running. The fresh DE will cling to the clean filter and start doing its job.

You need to be somewhat gentle when handling the filter grids. If they get torn or worn out they will need to be replaced.

A tear in the filter grid will allow DE to get into your pool. You will notice when this happens by cloudy water coming from the pool filter returns.


In a cartridge filter, dirty water passes through a filter made out of polyester cloth or corrugated paper. Instead of backwashing, you simply remove the filter and hose it off.

What these filters are made of will determine their useful life. After several years, or perhaps as many as eight years, it’s effectiveness in cleaning the pool’s water will become apparent and it will be time to replace the old filter.


The tank of a sand filter contains a thick bed of special grade sand. It is in this sand that the water filtration takes place.

The tiny particles of sand catch the dirt. To flush the sand pool filter, it will need to be backwashed. In backwashing the flow of water needs to be redirected.

All sand filters have a reverse flow valve or backwash valve connected to them. Always switch off the pump before moving the valve. Move the valve handle from the Filter to the backwash position.

With some it is a push/pull operation, with others it is a rotate operation.

Restart the pump and let the water flow in reverse through the filter for 3 minutes or until the water in the site glass runs clear.

Switch off the pump and move the valve to the RINSE or FILTER TO WASTE position (if the valve has one) or back to the FILTER position.

If you go to the RINSE position, operate the pump for 30 seconds to clear the filter & then switch off the pump and move the valve to the FILTER position.

Switch on the pump and allow it to operate as normal.


Avoid a Dangerous Situation!

Make sure all valves are ONbefore turning on the pump.

This Swimming Pool Filter page is an overview!

Always consult your owners manual for proper maintenance of your swimming pool filter.

The owners manual will have it’s own flushing and complete cleaning instructions. It’s IMPORTANT to follow the manufactures instructions thoroughly.