Pool filters are a crucial component of your pool system, maintaining the water's cleanliness and safety for swimmers. While your sanitizer (usually chlorine) kills bacteria and other contaminants, the filter is responsible for removing them from the water. Without a filter, your pool would become cloudy and filled with dead bacteria and debris, which is neither fun nor safe. Your filter should trap contaminants, be easy to clean and maintain, and last a long time in your pool's ecosystem.
Before choosing a pool filter, it's essential to understand your options. There are three main types: sand filters, cartridge filters, and D.E. (Diatomaceous Earth) filters. They're named after the type of filter media they use to remove contaminants. The choice of filter affects several factors, including cost, filtration speed, and the frequency of cleaning or replacement.
A pool filter is part of your pool's plumbing system. As water passes through it, it removes dirt and debris, producing clean, filtered water. Dirty water enters the filter, passes through the filter medium, and clean water flows back into your pool. Most people operate their filters for 6-12 hours daily, depending on the filter type and the frequency of pool use.
They are rated (or sized) in two ways: the filter rate and the filter area. The filter rate indicates the number of gallons of water that can be filtered per minute (GPM) and is matched to or exceeds the flow rate of your pump. The filter area's measurement refers to the total surface area of the filter media that is exposed to pool water, typically measured in square feet.
Sand filters work by circulating water through a large tank filled with sand. The typical sand used in sand filters is #20 silica sand, which captures particles that are 20 microns and larger in diameter.
The sand starts with rough edges, which help it grab contaminants and debris that pass through the filter. However, the more water that flows through, the smoother those edges become until they can no longer trap anything. Meanwhile, particles trapped within the sand accumulate, eventually blocking the water flow and reducing the filter's efficiency.
The built-in pressure gauge on the filter will warn you when the internal pressure increases, indicating it's time to backwash. This usually happens every 1-2 weeks or when the pressure rises 8-10 psi above normal.
Cartridge filters are as easy to maintain as sand filters, and if you have a small pool, they're more effective. Inside the tank, there's a plastic cylinder surrounded by pleated polyester filter media, capped on both ends. Water flows into the tank and then through the pleats, capturing debris as small as 10 microns before returning to the pool.
Just like sand filters, cartridge filters require cleaning, but the process is different. Instead of backwashing, you simply remove the cartridge from the tank and spray it down with a hose to remove debris and dirt. Occasionally, you can spray it with a filter cleaner or soak it in the cleaner if it's dirty.
Diatomaceous Earth, or D.E. filters, are the most expensive and maintenance-heavy option, but they do filter the smallest particles of all three filter types - 2-5 microns. D.E. filter tanks contain grids, sometimes referred to as "fingers", that are covered in diatomaceous earth. D.E. is a crumbly, white powder made from the crushed fossilized remains of tiny aquatic organisms called diatoms, which is heat-treated to serve as a filtration media. The powder is easy to find and is sold at most pool and hardware stores. The pressure gauge on the tank indicates when it's time to clean your D.E. filter, and they are backwashed in the same way.
You'll need to add more D.E. powder after each cleaning. It can be hard to determine how much to add; it's especially important to disassemble and clean the filter by hand at least once a year.
Feature
|
Sand
|
Cartridge
|
DE
|
Filtration (Microns)
|
20-40
|
10-15
|
2-5
|
Price Range
|
$
|
$$
|
$$$
|
Maintenance Level
|
Moderate
|
Low
|
High
|
Water Waste
|
Moderate
|
Minimal
|
High
|
Media Lifespan
|
5-7 years
|
1-3 years
|
1-2 years
|
Ideal Use
|
Large pools
|
Smaller pools
|
High-clarity water
|
The best filter for your pool depends on your specific needs, budget, and the level of maintenance you're willing to undertake. Regardless of which pool filter you choose, maintaining proper pool chemistry is crucial to extending its lifespan and ensuring optimal performance.
Sand filters come with a built-in pressure gauge that you should monitor and know the standard operation pressure. If the pressure increases by 8-10 PSI or if you notice a weak flow of water out of your pool return jets, then it's time to backwash your filter.
Unfortunately, there's no one answer for this. To know how much sand you need for your pool filter, you'll need to see the filter's specifications - typically it's diameter. Generally, you want to fill your filter about 65%-75% of its capacity with sand.
Yes, but you may need to adjust the plumbing of your pool, or purchase a new filter housing.
Just as with a sand filter, you should monitor your pressure gauge and be aware of the standard operating pressure. When the pressure increases by 8-10 PSI, or the returning flow of water to your pool is weak, it's time to clean the filter.
Cartridge filters are typically the easiest to care for.
Cartridge filters are a popular choice due to their compact size and efficiency.
Increased pressure, reduced flow, or visible wear on cartridges or media are signs that it's time to replace your filter.