Swimming Pool Filters: Knowing the basics

The two most important areas to monitor and control in your pool are the filtration and having the proper water balance. Keeping your swimming pool clean is the most essential part of pool ownership. The circulation of water allows the chemicals to keep the water sanitized and crystal clear. Without a filter your pool is basically a pond. Let’s dive in.

There are three main swimming pool filter types. A pool will most likely have a Diatomaceous Earth filter (DE), a Cartridge filter or a Sand filter. What does a pool filter do? Pool filters remove small particles from the water that are measured in microns. To put into perspective a micron is about .00004 inches. Improper filtration can allow your backyard to become a breeding ground for infections of the eyes and ears, digestive disorders, and can contribute to other unpleasant symptoms. 

First lets look at the DE filter. This filter is made from sedimentary rock that is composed of fossilized remains of billions of algae-like organisms, called diatoms. This type of filter offers the best filtration of the three, producing the cleanest water. In fact this filter has an impressive ability to filter down as low as 3 microns. Having trouble visualizing that? A human hair is 75 microns across. The DE filter uses the combination of a grid and DE powder which coats the grid to filter out dirt, debris, algae, and other organic matter. Something that is also a benefit to this type of filter is the ability to maintain a larger pool with a smaller filtration surface. A 48 sq ft filter can easily filter a 15,000 gal pool. This packs a big punch compared to a 200 sq ft cartridge filter or 300 lb sand filter. DE filters are also great that they can be backwashed. A technique that uses reverse water flow to push dirt and debris off the grid and out the backwash pipe. To clean a DE filter you simply backwash and add more DE powder to to the pool skimmer to recharge. The DE powder then re-coats the grids in the filter housing though the pools water circulation. These filters should be cleaned about 2-3 times a year and regularly inspected for any tears or rips to the grids.

Second, a popular choice among in ground pool owners is the Cartridge filter. This offers good water quality and is easy to maintain. They are made of a cloth or paper-like material that dirt, algae, and particles will stick to and allow clean water to flow through. They are incredibly easy to clean. Simply remove the cartridge and hose it down. It is best to soak the filter in cleaner for the recommended time and rinse clean with fresh water. For peak efficiency it is best to allow the filter to completely dry prior to reinstall. Pro tip is to purchase a second set of cartridge elements to eliminate the down time water is not in circulation. The down side though is they can not be backwashed. So every time they need to be cleaned they need to be taken apart. Depending on the size of the filter you could possibly be cleaning it more often. Smaller filters take up less space but will need to be cleaned more often and the water may not have as an efficient flow than a larger filter. This filter typically needs cleaning and replacement on average twice each a year.

Lastly, another popular choice due to the ease of maintenance is the Sand filter.

Sand filters are basically large tanks of a special graded sand. Water enters the filter and through the diffuser contaminants and debris get trapped in the grains of sand. This type of filter will only trap contaminants that are 40 microns or larger in size. Dirt is removed by backwashing periodically and the sand needs to be changed approximately every 3 years. Drawback is that this filter produces the lowest filtration of the three but its ease of maintenance makes it a popular choice. No need to take it apart unless you are going to have a pool professional change the sand. 

Speak to your pool professional and think about your long term budget to decide the right filter choice for your pool.