Swimming Pool Filter Buying Guide - Cartridge Filters
Posted by Sean McKenna on
If you have a rough concept of how the human body operates you are likely aware that the heart is the ‘pump’ that drives blood, via arteries, to the rest of the body. To expand the analogy a little further you may be aware that the function of our kidneys is to clean our blood by filtering the waste. In a pool circulation system the media filter plays the same pivotal role as the kidneys in our body. As water passes through the filter small micro-organisms are captured within the media so that the cleansed water can return back to the pool.
There are typically three styles of filter available for a swimming pool with each having their own benefits and drawbacks dependent on the unique parameters of the pool. The three types of filter are sand, cartridge, and diatomaceous earth which is often referred to simply as D.E.
Cartridge Filters
How do they work?
Cartridge filters, similar to sand filters, consist of a large tank body and internal media. The tank body of a cartridge filter contains one or more cylindrical shaped cartridges made of a synthetic fabric arranged into pleats. Water that enters the filter body passes through the synthetic fabric before returning to the pool.
How well does a cartridge filter perform?
Cartridge filters can remove particulate down to 15 microns. A micron is a measurement which is represented as one millionth of a meter. For reference; table salt is 100 microns, human hair is 70 microns and the limit of human visibility is 40 microns. So if someone says they have a certain type of filter because they can see the difference....refer them back to this blog.
How do I know what size of cartridge filter I need?
The effective filtering rate of a cartridge filter is determined by the amount of square footage of pleated material. Common sizes range from 50' – 700' ft2 and each square foot of material can handle .375 gpm or 15 lpm. This means that a 200' ft2 cartridge filter can support a pump that can produce 75 gpm of flow.
How much do they cost?
Cartridge filters are a more expensive option to install initially. They range in price from $900 - $2400 for residential systems. The main reason for the cost variance compared to a sand filter, which also features a similar polymeric tank body, is the cost of the cartridges themselves. The cost to replace filter cartridges will depend on the number and size of the elements. When filter cartridges are not cared for the replacement cost increases in step with buying frequency.
How much maintenance is involved in a cartridge filter?
Cartridge filters require a greater time commitment than a sand filter when they are due for cleaning. The frequency of cleaning is related to the unique parameters of the pool but the timing is based on an increase in pressure in the filter as noted on the pressure gauge.
To clean the cartridge filter elements they must be removed from the tank body and sprayed with a hose. It is also recommended to soak the cartridges in a solution to break down oils at least once per season. Once the cartridges are clean they can be re-installed in the tank body and the filter can be reassembled.
One of the greatest disadvantages of a cartridge filter is the need to dismantle the tank in order to clean the filter elements. If the two halves are not installed properly there can be small drips and leaks that will require reseating.
If the filter elements break down physically (ie. tear in material) they will need to be replaced. When cleaning and soaking the filter elements does not produce a reduced pressure that would suggest they would need to be replaced.
What type of pool makes a great fit for a cartridge filter?
- an indoor or enclosed pool
- a pool with limited debris (leaves, pine needles, sand/silt)
- a pool that does not have frequent algae blooms
- a pool with a high flow rate (large pump)
- a pool with an automatic cover
- a pool with hands-on owners
