There is nothing quite as refreshing as jumping into the pool on a hot summer day; the crystal-clear water cool and rejuvenating. Now imagine jumping into pool full of cloudy water, riddled with dirt and debris. The experience isn’t quite the same, is it? Fortunately, the former, idyllic pool is the norm thanks to pool filters! Pool filters remove dirt and debris and are paramount to maintaining a clean swimming pool. Below you will 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 also increase chlorine’s efficiency in killing bacteria, fostering a healthy swimming pool environment.
Types of pool filters
The three main types of pool filters are sand, cartridge, and diatomaceous earth.
Sand filters involve a tank full of sand that traps contaminants as water percolates through. While sand appears smooth to the naked eye, when viewed under a microscope 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 millionth of a meter. To put their miniscule size into perspective, 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.
Overtime, particles trapped in the sand build up and render the filter less effective. The 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. A plus for sand filters, 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 5-7 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 filters:
- Least expensive
- Low maintenance
- Straightforward operation
- Available for any pool size
Cons of sand filters:
- Least effective filtration
- Backwashing may waste water
- Backwashing may alter pool’s chemical balance
Cartridge filters consist of pleated cartridges that capture 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 10-15 microns range; a higher filter efficiency than sand filters. However, they are more expensive than sand filters and involve a different, yet simple maintenance process.
Similar to sand filters, pressure in the tank will increase 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: Maintaining a Pool Filter Cartridge
Pros of cartridge filters:
- Efficient filtration capabilities
- Less water waste due to no backwashing
- Easy to clean and replace filters
Cons of cartridge 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) 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 at a cost as they are the most expensive and most maintenance-intensive pool filters on the market.
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. This is where it gets a little tricky. 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. Lastly, at least once a year, you should also disassemble the filter and thoroughly clean the grids with a hose.
Pros of DE filters:
- Most effective filtration
- Backwashing only necessary every few months
- Filter grids last several years if properly cared for
Cons of DE 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 the one that best aligns with your pool’s needs and your personal preferences. When choosing a filter, consider filtration capability, initial cost, ease of operation, and maintenance routines and maintenance costs. Learning about the different types of filters will help you make the best choice for you and your pool! Although, whichever 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.
Also, Filbur is a tried-and-true pool filter brand that can provide safe, 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.
How much do pool filters cost?
Pool filters 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.
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 lastly 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.
Also, 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.
Do you need a pool filter?
Yes, you need a pool filter. Filters 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.
The exception is certain small volume pools that don’t 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
If you have any further questions about pool filters or need help selecting the best pool filter for you, please don’t hesitate to contact us.