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How Swimming Pool Filters Work

Clear water swimming pool

One of the most important elements of a swimming pool’s circulation system is the filtration. For the pool’s water to be consistently clear, clean and sanitary filtration is a must. An improper and inadequate filter and pump system will most likely lead to cloudy and unsanitary water, which then becomes a potentially dangerous and unhealthy swimming environment.

Pool filters are necessary to keep pool water sparkling clear, cool, and clean. In this connection, it is important for every swimming pool owner to know how swimming pool filters work.

Pool Filter and Pump Systems

A swimming pool’s pump and filter basically work in a loop or cycle, with the need to add water in the pool, due to the tendency of the pool water to evaporate. The closed loop or cycle starts with the filter drawing water from the skimmer and the pool, and delivering it to the pump and motor. The pump has a sort of strainer, where the collected water passes through. This process removes bigger debris from the water before it is pushes through the pump. From the pump, the water goes through the filters, which will then remove any remaining contaminants and debris in the water. If there is a pool heater, the filtered water then goes through the water for temperature conditioning.  Once the water reaches the pre-set temperature, it then goes through the chlorinator before the treated and filtered water is pumped back to the pool.

The process is quite simple, and can be set on automatic. As a general rule, one cycle a day is sufficient for pool water maintenance.

Three Types of Pool Filters

A House with a Swimming Pool

The three types of pool filters are: sand filter, diatomaceous earth (DE) filters, and cartridge filters. Each of these filters have their pros and cons. Choosing which one to use largely depends on the recommendation of pool professionals and local inspectors, based on the local building code. It is important to note that the type and size of filters are very important aspects for the ease of maintaining and cleaning the pool.

  • Sand Filters

Sand filters are the oldest and most common type of filtration used. Water is filtered through “sand” to collect debris of 20-50 microns. For visualization regarding microns, a human hair is about 70 microns and most bacteria around 1 micron. The sand can be high grade silica, or a combination of gravel and coarse sand. In some models, the granular media is crushed grass instead of sand. This type of filter is the simplest, yet dependable method of filtering pool water. Sand filters will last for a decade or so before needing replacement. However, sand filters need to be cleaned on occasion by backwash – which is reversing water flow through the filter, to prevent caked sand and build-up of debris. Chemical cleaning may also be done when deemed necessary.  On the cons of this type of filter, sand filters will not filter out very fine particles, and backwashing causes loss of water, heat, and chemicals.

  • Cartridge Filters

Cartridge filters are mostly recommended for smaller pools. They are composed of cylindrical layouts of pleated paper or polyester. This type of filter has a bigger surface, making for lesser clogs and easier maintenance. They run on lower pump pressure, therefore there’s backpressure on the pump, making for more water flow and turnover. Cartridge filters are more effective in filtering smaller particles in the 10-25 micron range. They are easy to clean and replace, and leave a smaller footprint, thus they are more eco-friendly. This type of filter cannot be cleaned by backwashing. The filter is cleaned at least once every season by hosing the cartridge elements. Another option is to remove the elements from the filter housing, replace them with clean ones, and then hose the cartridge elements off. Cartridge filters are more expensive, but the savings on water and chemicals make up for it. They are also more suited for smaller pools.

  • Diatomaceous Earth (DE) Filters

DE filters are minute fossilized exoskeletons of plankton or tiny diatoms. They are used to coat grids of filtration elements, acting as sieves to trap and remove debris as small as 2-5 microns. This type of filter is considered the most efficient option. It requires a large space in the pump room as it needs to be completely submerged in the water tank. Water to be filtered can be pushed or pulled through the DE filter.  As with sand filters, DE filters can be backwashed for cleaning. However, some DE will be lost during backwash and would require replacement of DE powder.

Energy Efficient Tips for Pool Filters

Low section view of a person in a swimming pool

Keeping the drains clean and clear from debris will help make the pool energy efficient. The more debris there is in the pool drains, the harder the pool filter and pump work, thus the more energy is used. Keeping the pool drains clean will ensure that the filter and pump system work smoothly and efficiently.

Reducing pump running time should be considered. In some cases, a single run of the water through the filter is sufficient to keep the pool water sparkling clean.

Regular inspection of the pool’s filters is a must to make sure that no dirt and grime has accumulated in the filters. Dirty filters are inefficient and require more energy to power up.

Pool covers will help save on money and energy. An uncovered pool loses up to 20,000 gallons of water through evaporation. Covering it will minimize water evaporation, thus saving on water consumption. If the water is heated, more energy is saved in the end. Also, pool covers are safety measures for homes with small children.

Pool Master is a leading swimming pool contractor in Thailand. The company has been providing excellent products and services to a wide range of clients for over two decades now. The company motto “Clean water and great pool parties make people smile!” is a testimony to its thrust. And that is to have happy, contented clients.

Contact us today. Consultation is FREE.