The filter type that is rapidly growing in popularity is the cartridge filter. The reason that it is becoming more popular is that it is inexpensive, fairly simple to operate, and no backwashing is required. Since no backwashing is required (and thus no water loss), many municipalities prefer that cartridge filters are used to prevent chlorinated water from entering the storm sewer system or the sewer system.
Cartridge filters were developed in the 1950’s originally for spas and later for above-ground pools, but are now being used on in-ground pools. This cartridge can filter down to 10-20 microns, which is very small. For example, a grain of salt is approximately 100 microns and the human eye can see down to approximately 40 microns.
The cartridge appears similar to a car’s air filter—but a pool filter cartridge is much taller. The cartridge is made from a synthetic pleated material, and as water passes through it, dirt and debris is trapped. As this dirt and debris is trapped, the filter becomes dirty which increases the pressure and decreases the water flow—thus rendering the filter inefficient and oftentimes incapable of physically cleaning the pool water. When this occurs, it is necessary to clean the filter.
As mentioned previously, cartridge filters cannot be backwashed, but rather the cartridge is removed from the filter tank and cleaned.
How often do I need to clean the cartridge?
We recommend cleaning the cartridge when the pressure increases 8-10psi (as viewed on your filter pressure gauge) over the clean starting pressure or a minimum of once every six months. If the filter is not cleaned when the filter pressure increases, it could result in damage to the cartridge.
How do I clean my cartridge filter?
We recommend following the manufacturer’s operating instructions for cleaning your cartridge filter. Most of these are available online at your filter manufacturer’s website. Following is a general guide if you are unable to find your manufacturer’s operating instructions.
- Turn the pump off.
- Remove the cartridge from the filter housing.
- Use a garden hose with a nozzle attached to clean the cartridge. Working from the top down, spray the cartridge with a particular emphasis on the areas between the outer pleats. Rinse until all dirt and debris is removed. A pressure washer is not recommended, as the high pressure can damage the cartridge.
- It is helpful to use a cartridge cleaner, which helps removes oils and scale. If you do use a cleaner, be sure that the cleaner is made specifically for cleaning pool cartridges.
- Inspect the pleats to be sure that they are straight, and that there are no visible holes.
- Clean and remove dirt and debris from inside of the filter tank and from the filter o-ring.
- Replace the filter back into the filter housing.
- Reassemble the filter housing.
- Turn the pump on (standing away from the filter) and check for leaks.
Note: If the filter has a manual air relief valve, turn it to the full open position any time that the pump is first turned on. After water comes out of the air relief valve, turn it to the closed position.
It can be helpful to have a spare cartridge so the cartridge can be immediately replaced while the dirty cartridge soaks.
Typically the cartridges must be replaced every 1-5 years, depending on how well they are cared for.