The Types of Pool Filters and the Differences between Them

Sand vs. Cartridge vs. Diatomaceous Earth

When it comes to keeping your pool clean and clear, there are a few different types of filters to choose from. Sand filters, cartridge filters, and diatomaceous earth (DE) filters are all commonly used in pool filtration systems. Each type of filter has its own unique advantages and disadvantages, so it’s important to understand the similarities and differences between them in order to make an informed decision.

Let’s start by viewing how pool filters are compared to one another and therefore their overall similarities. Pool filter ratings are determined by a number of factors, including the size of the filter, the flow rate of the water, and the type of filter media used. The two most commonly used rating systems for pool filters are the American National Standards Institute (ANSI) and the Water Quality Association (WQA).

The ANSI rating system is based on the filter’s ability to remove dirt and debris, as well as its ability to retain the dirt and debris once it has been captured. The rating is determined by performing a series of tests on the filter, including a “dirty filter” test and a “clean filter” test. The results of these tests are then used to calculate the filter’s “single-pass efficiency” rating, which is expressed as a percentage.

The WQA rating system is based on the filter’s ability to remove a specific size of particle from the water. The rating is determined by performing a series of tests on the filter, including a “challenge” test where a specific size of particle is added to the water, and the filter’s ability to remove that particle is measured. The results of these tests are then used to calculate the filter’s “micron rating,” which is expressed in microns.

Both rating systems are generally considered to be reliable and accurate, but it’s important to note that they measure different things. The ANSI rating system measures the filter’s ability to remove and retain dirt and debris, while the WQA rating system measures the filter’s ability to remove particles of a specific size. When choosing a pool filter, it’s important to consider both the ANSI and WQA ratings in order to get a complete picture of the filter’s performance.

It’s also important to keep in mind that both rating systems are based on ideal conditions and laboratory testing. Factors such as water chemistry, flow rate, and pool usage can affect the filter’s performance. Therefore, it is always recommended to consult with a pool professional before making a decision.

In terms of other similarities, all three types of filters use a mechanical filtration process to trap dirt and debris, and they all require some degree of maintenance to keep them running efficiently. Additionally, all three types of filters can be used in conjunction with other types of pool equipment, such as chlorine generators or ozonators, to keep the water in your pool clean and clear.

The best filter for an in-ground residential swimming pool in the Sun Belt depends on a variety of factors such as the size of the pool, the bather load, the desired water flow rate, the budget and the pool owner’s maintenance preference. However, generally speaking, a Cartridge filter and a Diatomaceous Earth filter are considered to be the best options for in-ground residential pools in the Sun Belt.

Cartridge filters are the best option for most in-ground residential pools in the Sun Belt. They use a pleated cartridge to filter the water, which increases the filtration area and allows for a higher level of filtration. Cartridge filters are relatively low maintenance, but the cartridges will need to be cleaned or replaced more frequently than the sand in a sand filter. Cartridge filters are commonly sold in two different models either a single cartridge unit or a four cartridge unit. The main difference between a single cartridge and a four cartridge swimming pool filter is the number of cartridges used in the filtration process.

A single cartridge filter uses one cartridge that contains a pleated filter element. This element captures dirt and debris in the water as it flows through the filter. Single cartridge filters are typically smaller and less expensive than four cartridge filters, and they are ideal for smaller pools or for pools with lower bather loads.

A four cartridge filter, as the name implies, uses four cartridges that contain pleated filter elements. These elements work together to capture dirt and debris in the water as it flows through the filter. Four cartridge filters are typically larger and more expensive than single cartridge filters, but they offer a higher level of filtration and are ideal for larger pools or for pools with higher bather loads.

One of the main advantages of a four-cartridge filter is that it has a larger filtration area, which means it can handle a larger volume of water and more dirt and debris. Additionally, when one cartridge becomes clogged, you can easily replace it with a new one without interrupting the filtration process, while still maintaining a high flow rate.

In summary, a single cartridge filter is a good option for small pools or low bather loads, while a four-cartridge filter is a better option for larger pools or high bather loads as it offers a larger filtration area, more flexibility, and less interruption on the filtration process.

Diatomaceous Earth (DE) filters are similar to cartridge filters in that they use a pleated filter element, but instead of a cartridge, they use a fine powder made from the fossilized remains of tiny aquatic creatures called diatoms. DE filters are highly efficient at removing very small particles, such as bacteria and algae, and are considered the most efficient type of pool filter. However, DE filters require more maintenance than the other types, as the DE powder will need to be added regularly and the filter elements will need to be cleaned or replaced more frequently. DE filters are highly efficient at removing very small particles, such as bacteria and algae, which are common issues in the sunbelt region where the water is warmer and UV rays are stronger. DE filters are considered the most efficient type of pool filter, but they do require more maintenance than the other types.

Sand filters are the most traditional type of pool filter, and they use a bed of sand to trap dirt and debris. Water is pumped through the filter, where it is forced through the sand, which acts as a mechanical filter to trap dirt and debris. Sand filters are relatively low maintenance, and the sand can be easily cleaned or replaced as needed. Sand filters are not considered the best option for in-ground residential pools in the Sun Belt because they are less efficient at removing small particles and they can be more prone to clogging, which can cause a decrease in water flow and pressure.

Some of the additional maintenance that would be required for both a DE and sand filters but not required for a cartridge filter is back-washing. Back-washing a swimming pool filter uses a significant amount of water, but the exact amount will depend on the size of the pool, the flow rate of the water, and the duration of the backwash.

On average, it takes about 50-100 gallons of water to backwash a standard sand or DE filter. A backwash typically lasts between 2-5 minutes, but this can vary depending on the condition of the filter media.

It’s important to note that back-washing is an essential part of maintaining your pool filter, and it’s necessary to remove dirt, debris, and other contaminants that have accumulated in the filter. However, you can reduce the amount of water used during the backwash by ensuring that the filter is cleaned regularly and by scheduling back-washing during periods of low water usage.

Some pool filter systems also have a feature called a “filter re-circulation” or “filter cleaning” mode, which uses less water than back-washing and also less time, but it still effectively cleans the filter. This mode is also called “backwash on demand” or “self-cleaning filter” and it can save a significant amount of water.