Pressure Gauge:
The Pressure gauge is there for a reason so try to make sure it works, it will tell you when you need to backwash the filer, correct backwashing can save a considerable amount of makeup water each year.

Filter Sand, Pads or Cartridge:
Fitter sand should release all of its trapped debris during a backwash but is does not normally happen this well. After a period of a couple of years with a lot of perspiration & body fats & suntan oils in the water the sand becomes sticky & will not release debri easily.

You will need to soak the sand in the filter tank in a solution of pool acid or a sand filter cleaner solution to remove the components which have attached themselves to the sand.

Also one of the biggest reasons a Sandfilter clogs up prematurely is because the backwash line from the filter to the street or sewer is to small or to long. (40mm for 6M - 50mm for 6-12M 80mm over 12 M.)

The pads in a DE filter are there to hold the filter material (the DE Powder) & in theory should not get contaminated with debri, but they do. More than anything, they absorb calcium & other chemicals from the water which reduce their effectiveness. These chemicals can usually be removed with a 24 hour soak in a 10:1 water & pool acid mix.

The biggest mistake with a DE filter is to use to little powder & not cover the pads completely also letting air become trapped in the top of the filter tank stops water getting to the pads in that area to coat them with DE. - Always release the air from the tank prior to adding new DE powder.

Always check for holes in the pads especially in the stitching or on corners these will allow DE & debri right on through & back to the pool.

Cartridge filters tend to have the same problems as the other two, especially if they are not cleaned often enough, they will need a good soak on a two monthly basis in cleaning solution. Filter Internals: This refers to the parts which make up the internal of the filters such as the base laterals in a sand filter, these allow the water to pass through but not the sand. they can become clogged after a period of years & should be inspected & cleaned each 6-8 years when the filter sand is replaced.
The spider supports for the pads in a DE filter need to be checked for cracks & must all fit tightly to the pad connecting tubes.

The Cartridge filters normally have very little of internals but they must always fit well to stop any bypass. A cartridge filter is similar to the air cleaner filter in the car, made of a convoluted material. They need to be removed from their tank & cleaned by hosing down on a regular basis. Use a good strong hose nozzle, (your finger will get sore if you try to use it to spray the cartridge). Spray between all of the flutes. If the cartridge is very dirty of the spray won't remove the dirt then try soaking in a cartridge cleaner solution from the pool shop.

Diatomaceous Earth Filters

These filters have a set of pads inside which must be coated with the DE. The DE is the filter & it removes the dirt from the water passing through. When the dirt builds up to a point that it reduces the flow of water, the DE & its dirt must be removed.

Some filters have a valve which allows you to reverse the flow through the filter to remove the DE & dirt. This works on some but not all.

In most cases you will need to remove the lid of the filter tank & take out the pads & give them a good hose down. In many cases you can use the reverse flush method normally & then each six months or so remove the pads for a good clean.

After you replace the pads & refit the lid, you will need to start the pump & add more DE though the skimmer box.

Usually 1lb per 10SqF or 500gms per SqM

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 & some a rotate operation.

Restart the pump & let the water flow in reverse through the filter until the water in the site glass clears or about 3 minutes.

Switch off the pump & 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 the operate the pump for 30 seconds to clear the filter & then switch off the pump & move the valve to the FILTER position.

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

A cartridge filter is similar to the air cleaner filter in the car, made of a convoluted material. They need to be removed from their tank & cleaned by hosing down on a regular basis.

Use a good strong hose nozzle, (your finger will get sore if you try to use it to spray the cartridge). Spray between all of the flutes.

If the cartridge is very dirty of the spray won't remove the dirt then try soaking in a cartridge cleaner solution from the pool shop.