There is nothing quite as refreshing as jumping into the pool on a hot summer day. Now imagine jumping into a pool full of cloudy water, riddled with dirt and debris. Fortunately, clear, safe pool water is the norm thanks to pool filters and treatment chemicals. Pool filters remove dirt and debris that can make clear pool water a murky mess. In this article, you can learn about pool filters, their many variations, and how to select the best filter for your swimming pool.
What is a pool filter?
A pool filter is a component of a pool’s filtration system that removes dirt and debris from water. A pump pulls water to the filter, the filter removes dirt and debris, and then clean water is returned to the pool through return jets on the pool walls. Pool filters not only keep your water clean and clear, but they also increase chlorine’s efficiency in killing bacteria, fostering a healthy swimming pool environment.
Do I need a pool filter?
Yes, pool filters are essential in maintaining safe, clear pool water. They remove dirt, debris, and insects and allow for better distribution of chlorine to combat bacteria. A pool filter is essential to a healthy pool environment.
Small volume pools may not require a filter but still require regular water treatment. To maintain a pool without a filter, you need chlorine as well as a flocculant. A flocculant is a chemical that groups impurities that float in the water, so they can be easily removed with a net or other cleaning device.
Learn More: How to accurately test pool water
Types of pool filters
The three main types of pool filters are sand, cartridge, and diatomaceous earth.
Sand pool filters
Sand filters utilize a tank full of sand that traps contaminants as water percolates through. While sand appears smooth to the naked eye, each grain has prickly, rough edges that grab contaminants. Dirt and debris remain trapped in the sand, and clean water travels to the bottom of the tank and returns to the pool.
Sand filters trap contaminants in the 20 to 40 microns range. A micron is one micrometer or one-thousandth of a millimeter. For reference, a strand of human hair is about 70 microns wide. Debris that is 20 to 40 microns in size is indeed small, but sand filters are the least effective compared to other pool filters, as cartridge and DE filters can trap even smaller particles.
What is backwashing a sand pool filter?
Over time, particles trapped in the sand build up and render the filter less effective. This buildup prevents proper water flow and raises the pressure in the tank. A pressure gauge on the side of the filter alerts you to pressure changes and indicates when it’s time to perform maintenance. One benefit of sand filters is that maintenance is simple and easy. All you need to do is backwash the filter, which means running the water in the reverse direction to flush out debris. When more frequent backwashing is required, you should replace the sand, but this is only necessary every 5 to 7 years. Keep in mind that if you frequently backwash your filter, you can disrupt your pool’s chemistry and water levels. You may need to rebalance the chemicals and refill your pool.
Pros of sand pool filters
- Least expensive
- Low maintenance
- Straightforward operation
- Available for any pool size
Cons of sand pool filters
- Least effective filtration
- Backwashing may waste water
- Backwashing may alter pool’s chemical balance
Cartridge pool filters
Cartridge filters consist of pleated filter media that captures debris when pool water flows through a tank. The pleats trap contaminants as small as 10 microns, and clean, filtered water returns to the pool. Most cartridge filters trap debris in the 10 to 15 microns range, a smaller range of sizes than sand filters can handle. However, cartridge filters are more expensive than sand filters and involve a different yet simple maintenance process.
How to clean a pool filter cartridge
Like with sand filters, pressure in the tank increases when the cartridges are dirty. When the tank’s pressure gauge indicates high pressure, it is time for maintenance. To clean your cartridge filter, take the cartridge out of the tank and spray it with a hose to remove dirt and debris. When the cartridges are especially dirty, you may need to gently brush them to loosen the debris. However, brushing weakens the filter media, so the more often you do it, the more often the cartridges need to be replaced.
Learn More: How to maintain a pool filter cartridge
Pros of cartridge pool filters
- Efficient filtration capabilities
- Less water waste due to no backwashing
- Easy to clean and replace filters
Cons of cartridge pool filters
- More expensive (higher initial purchase and maintenance costs)
- Deep cleaning required 1-2 times a year
- Need to replace cartridges every 2-3 years
Diatomaceous Earth (DE) pool filters
Diatomaceous Earth (DE) filters contain grids covered in a crumbly white powder that captures unwanted contaminants but allows water to flow through. The powder is made from crushed fossils of single-celled algae called diatoms. Diatoms contain high amounts of silica, which lends DE the bulk of its filtration power. Silica is also a major component of sand.
DE filters have the strongest filtration capabilities and can capture particles as small as 5 microns. DE filters provide the highest water quality for your pool, but they are the most expensive and most maintenance-intensive pool filters on the market.
Can I backwash a DE pool filter?
Maintenance is required when the tank’s pressure gauge indicates high pressure. Like sand filters, DE filters are backwashed, but afterwards, you must add more DE powder to the filter. However, there are some complications. Pool grade DE is toxic if inhaled in large amounts and can irritate your lungs, so it is recommended to always wear a mask when handling DE powder. Also, your city may have DE disposal restrictions, such as no backwashing into streams or sewer systems. We recommend contacting your municipality regarding local DE disposal regulations. Finally you should also disassemble the filter and thoroughly clean the grids with a hose at least once per year.
Pros of DE pool filters
- Most effective filtration
- Backwashing only necessary every few months
- Filter grids last several years if properly cared for
Cons of DE pool filters
- Most expensive
- High maintenance
- DE powder is toxic and should not be inhaled
- Potential disposal restrictions
What is the best type of pool filter?
The best pool filter is dependent on the pool and the pool owner. The filter that best aligns with your pool’s needs and your personal preferences is the best option for your pool. When choosing a filter, consider its filtration capability, initial cost, ease of operation, and maintenance costs. Learning about the different types of filters will help you make the best choice for you and your pool. Regardless of which type of filter you choose, select the largest size appropriate for your pool. Large filters require less maintenance and clean up poor water conditions much faster than smaller filters.
Filbur pool filters
Filbur is a reliable pool filter brand that provides safe and dependable protection for your pool. Filbur pool filters are made of reinforced center cores, premium filter media, and antimicrobial end caps that work together to provide advanced protection and ensure clean, contaminant-free pool water. Filbur replacement cartridges are made to fit the original manufacturer’s specifications precisely, so even maintenance and filter replacements are a breeze.
Neo-Pure pool filters
Neo-Pure offers a wide variety of pool filters compatible with a host of other brands. Neo-Pure cartridges utilize a high-strength polyester media that holds its rigidity through multiple cleanings. Their trilobal pleated filter media features an increased effective surface area, increasing the holding capacity and efficiency of each filter.
In-ground vs. above ground pool filters
Both in-ground and above ground pool filters keep a pool clear of dirt and debris. Water is pumped to the filter, then either sand, cartridge, or DE media filters the water, and clean water returns to the pool. The main differences between in-ground and above ground pool filters are size and location.
In ground pools are typically larger than above ground pools, and their filters are designed to handle a higher flow rate and larger volumes of water. Above ground pool filters are generally smaller versions of in-ground pool filters.
In-ground pool filters are located near your home or as close to the electrical panel as possible, while above ground pool filters are placed below water level next to the pool. Since in-ground pool filters must contend with more feet of plumbing and gravity, their filter systems have to work a little harder and may require more skimmers, jets, and suction lines than above ground systems.
How much do pool filters cost?
Pool filter systems typically cost between a couple hundred and a couple thousand dollars depending on the type of the filter and the filter’s size and complexity. In general, sand filters are the least expensive and DE filters are the most expensive. Sand, cartridge, and DE filters must all be replaced or replenished over time. You can find a 50-pound bag of pool filter sand for about $25. Likewise, replacement cartridges can cost anywhere from $20 to over $100 depending on the type needed for your pool. Bags of diatomaceous earth are more expensive than sand and cartridge filters and are less environmentally friendly.
If you have any further questions about pool filters or need help selecting the best pool filter for you, please do not hesitate to contact us.