Cartridge pool filter buying guide

Designed exclusively for above-ground pools measuring less than 35 m3, cartridge filters are the most basic of all pool filters but are also the easiest models to install. In fact, these filters are often supplied with smaller above-ground pools.

This all-in-one system comes with the filter cartridge, pump and connecting hoses. A cartridge filter is straightforward to install, compact and inexpensive. But it will still be able to filter fine particles from your pool and get rid of any impurities.

All you have to do to set up is to place the filter to one side of your pool and connect it to the hoses and your electrical supply.

The cartridge itself needs to be checked regularly and should be changed every 2 to 3 weeks depending on how often you use your pool. You will therefore have to be prepared to cover this cost.

Cartridge filters should be chosen according to pump flow rate which must be sized to your pool.

Cartridge pool filters, also known as above-ground pool filters, are basically made up of a cartridge and a pump.

These cylinder-shaped devices contain a cartridge made up of synthetic or plant-based fibres. The cartridge is usually folded like an accordion for a larger surface area and, in turn, greater filtering capacity.

The pump is designed to draw water into the filter where it is cleaned of any impurities. It is then sent back out through the pool's return inlets.

That's why there are two hoses: one serves as the water inlet and the other is the filter outlet which is connected to the pool inlet.

While pool cartridge filters do have undeniable advantages, it's important to be aware of the limitations of this type of filtering system before you invest.

Benefits of cartridge filters

• Cartridge filters are the least expensive of all pool filtering systems. They range from about £30 to £100 depending on the size of your pool.

• A cartridge filter is an all-in-one system which is easy to install and maintain.

• Cartridge filters are able to filter fine particles from the pool. In fact, they are more efficient than sand filters and can deal with particles of around 10 to 30 microns in size (a micron being the equivalent of one thousandth of a millimetre).

• These filters don't take up a lot of room.

Drawbacks of cartridge filters

• Cartridge filters are only suitable for above-ground pools with volumes of less than 35 m3.

• The cartridge has a limited service life (about 2 to 3 weeks). It must be changed regularly which does involve additional costs.

• These filters do not enable you to use flocculant (a product designed to improve filtering performance) or certain types of algaecides.

In order to choose the right cartridge filter, be sure to check the flow rate of the pump as indicated by the manufacturer. For optimum performance, your cartridge filter should be able to filter your entire pool in around four hours or a maximum of six hours.

The flow rate is given in metres cubed per hour (m3/h) so the flow rate must correspond to the volume of your pool divided by four (or six for less efficient performance). For an above-ground pool with a volume of 20 m3, for example, you'll need a flow rate of 5 m3/h.

It's worth noting, however, that the flow rate of this type of filter will rarely go beyond 10 m3/h.

Cartridge filters don't need any special type of enclosure for installation especially since they will only stay in place for swimming season.

You can install your cartridge filter directly on the ground beside the pool. You'll then need to connect the filter to your electricity supply.

Next, you'll have to connect a water inlet hose between the cartridge filter and the pool and a return hose between the filter and the pool inlet.

Cartridge filters don't generally need a lot of care beyond cleaning the cartridge itself. This should be done about twice a week.

To so do, simply turn off the filter and remove the cartridge before cleaning the filter under running water or using a special brush designed for this purpose. Finish by placing the cartridge back inside the pool filter.

In order to remove any oily substances from the filter (such as sun cream) you can soak it in a special cleaning product.

If any impurities remain, you'll have to change the filter entirely. Generally speaking, this should be done every 2 to 3 weeks.