What are the Different Types of Pool Filters?

The first step in deciding what pool filter is best for your pool is knowing what filters are available and how they work.

Types of Pool Filters

Sand Pool Filter

A budget-friendly option that requires minimal maintenance, sand filters are ideal for both in-ground and above-ground pools.

How a Sand Filter Works

As pool water is pumped through the filtration system, it is pushed through a filter tank filled with sand. Contaminants and debris are caught on the spiky edges of each sand particle. Standard sand in sand pool filters can filter contaminants that measure 20 microns or larger. As water continuously flows through the filter, the contaminants trapped between the sand build up, eventually restricting the water flow, increasing internal pressure, and reducing the filter's efficiency. However, with proper maintenance, a sand filter will keep your pool clear and clean.

Sand Filter Maintenance

While you only need to replace the sand in your pool filter every 5 to 7 years, you must occasionally backwash the filter to clear out all the built-up debris. This easy cleaning method reverses the flow of water back through the sand filter, flushing debris out to waste. Knowing when to backwash a sand filter is easy: a pressure gauge on the sand filter alerts you when internal pressure increases, indicating it's time to backwash.

Sand Filter Advantages & Disadvantages

Advantages:

• Low upfront cost
• Easy maintenance
• Sand lasts 5 to 7 years before needing to be changed
• Filtration efficiency can be boosted with additives or alternative media

Disadvantages:

• 20-micron filtration is the least effective of the three types
• Backwashing is viewed by some as not environmentally friendly due to water waste

Cartridge Pool Filter

Cartridge filters are slightly more expensive than sand filters and require a bit more maintenance, but they can be more effective and energy-efficient, especially for larger pools.

How a Cartridge Filter Works

Rather than using sand as a filtering agent, cartridge filters contain a pleated polyester filter. As pool water is pumped through the cartridge filter tank, water flows into the tank and through the pleats, capturing debris as small as 10 microns. Clean water then returns to your pool.

Cartridge Filter Maintenance

Over time, as the filter collects debris, you must remove the pleated cartridge from within the tank to clean it. Unlike a sand filter that can be backwashed, to clean a cartridge pool filter, you need to remove the cartridge and spray it down with a hose until the water runs clear. While this requires slightly more work than maintaining a sand pool filter, it wastes less water than backwashing.

Cartridge Filter Advantages & Disadvantages

Advantages:

• Filters contaminants as small as 10 microns
• No backwashing
• Less water waste
• Performs well at low speeds, such as with variable-speed pool pumps
• Cartridge inserts are inexpensive to replace

Disadvantages:

• Requires slightly more manual work than sand pool filters
• The cartridge needs to be replaced every 2 to 3 years
• Deep cleaning is required 1 to 2 times yearly

Diatomaceous Earth Pool Filter

Diatomaceous earth (D.E.) filters can filter particles as small as 2 to 3 microns, providing the cleanest, clearest water of all three types of pool filters. However, D.E. filters are more expensive and require the most maintenance of the three pool filter options.

How a Diatomaceous Earth Filter Works

Diatomaceous earth is a white powdery substance made from the crushed fossils of aquatic organisms called diatoms, often referred to as "water polishers" because they leave pool water sparkling clean. D.E. pool filter tanks contain several grids coated with diatomaceous earth. The diatoms act like a sponge — water can pass through, but microscopic impurities like dirt, algae, and some forms of bacteria cannot.

Diatomaceous Earth Filter Maintenance

Like sand filters, a pressure gauge on the tank lets you know when to backwash. Be aware that some locations may have regulations specifying how to dispose of used D.E. Further grid cleaning may be necessary each year to help your pool filter operate more efficiently and last longer. In this case, you would remove the grids from the filter tank and hose off excess dirt before soaking them in a filter cleaning solution to remove body oils, suntan lotions, organic materials, and minerals. After every cleaning, you'll need to add more D.E. powder. Instead of adding the D.E. powder to the grids, you'll get better results by adding it through your pool's skimmer.

Diatomaceous Earth Filter Advantages & Disadvantages

Advantages:

• The highest degree of water clarity
• Filters contaminants as small as 2 microns
• D.E. powder can be added through the pool skimmer
• No caustic chemicals are required for cleaning

Disadvantages:

• Highest cost filter
• Requires more maintenance
• The grid needs to be replaced every 2 to 3 years
• Backwashing wastes water and may be restricted by location
• D.E. powder can be harmful if inhaled (wear a mask!)

Choosing the Right Size Filter

Whether you decide on a Sand Filter, a Cartridge Filter, or a D.E. Filter, it's essential to select a pool filter that is sized correctly for your pool. This ensures optimal performance and efficiency, keeping your pool water clean and clear.