What Are The 5 Best Pool Filters For Inground Pools?

Chlorine and other sanitizing chemicals are used to kill contaminants in the water, but they don’t actually remove debris from the water.

Pool systems use either a sand filter, cartridge filter, or DE (diatomaceous earth) filter to rid the water of microscope impurities. Without a filter, pools become cloudy and full of floating debris.

In this article, we’ll break down everything you need to know about each filter, so you can easily identify which will be the best pool filter for you.

Our Picks For Best Pool Filters?

We took a close look at the best pool filters available right now, then narrowed it down to only our top picks.

Best Overall (Recommended)

Best On A Budget

Best Sand Filter

Best Cartridge Filter

Best D.E Filter

Types Of Inground Pool Filters

There are a few different types of pool filters you’ll come across, but why might you choose one over the other?

Sand Filters

A sand filter is comprised of #20 silica sand that’s housed in a large tank.

Once water is pumped out of the pool, the filter grabs particles in the water as small as 20 microns in size.

The more you use the filter, the more effective it becomes. This is because the debris it catches (which therefore build up in the filter) stops even smaller particles from passing through so they can’t be reintroduced to the pool.

The use of #20 silica sand is deliberate, as it has a specific, spiky grain measuring between 45 and 55 millimeters. These spikes allow it to grab hold of contaminants. However, as the years go by, the sand gets worn down becoming less effective and eventually needs replacing.

Pros:

• Budget choice for large pools ranging from $150 to $700
• Won’t clog as easily as other filters
• Provides plenty of use and sand only needs replacing every 3 to 5 years
• Some people replace the silica sand with ZeoSand (made from zeolite) or Filter Glass (recycled glass), both of which can provide improved filtration and increased longevity

Cons:

• Only catches 20 microns and larger. This means you’ll need to stay on top of your pool water chemistry and heavily rely on your sanitizer to get rid of bacteria and organisms under 20 microns.
• Requires you monitor the pressure gauge so you know when to clean the filter through backwashing
• The more pressure in the filter, the less effective it works

Cartridge Filters

Cartridge filters are the next step up in pool filtration, available in either single or quad style, filtering as small as 10 microns in the water.

The cartridge(s) uses a pleated polyester design to catch debris as water passes through it.

Single cartridge filters are good for smaller pools that get less use while quads use 4 cartridges to keep medium to large-sized pools clean.

Pros:

• Slimmer design than both sand and DE filters so they take up up the least amount of space
• Easy to clean by removing the cartridge(s) and hosing them down to remove debris. You can also go longer periods between cleaning compared to the amount of backwashing that needs to be done with a sand filter or DE filter.
• Works well with variable speed pool pumps, which can have slow speeds at times

Cons:

• More expensive than sand filters. Average cost is around $700, but prices range from $300 to $1,800. Replacement cartridges also range depending on your filter model. They can cost anywhere from $30 to a few hundred dollars.
• More work involved when cleaning this filter as you can’t backwash it. You’ll have to remove the filter every 2 to 6 weeks and hose it down, with a deep cleaning done once a year 
• Filters need replacement every 2 to 3 years

D.E Filters

The top of the line pool filter is a DE filter (diatomaceous earth). This filter is the most expensive but also the most effective, grabbing pollutants as small as 1 to 3 microns in size.

The filtering process uses, surprise surprise, diatomaceous earth – a powder made from fossilized diatoms (translation: an ancient form of microalgae).

After the filter is installed, the powder is mixed with water and poured directly into the pool skimmer. The pool pump will suck in the DE mixture, passing it to the filter. The DE then sticks to the filter grids where it works to trap debris.

Of note, DE powder can be harmful if inhaled, so always wear a chemical mask when handling it.

Pros:

• Best filter to buy if you want the cleanest possible pool water
• Easy to add DE powder via the pool skimmer
• Cleaning the filter isn’t that difficult

Cons:

• Most expensive filter, averaging $800 to $900.
• Cleaning is easy but labor intensive. Filter should be backwashed and rinsed monthly (in accordance to its pressure gauge). A deep cleaning should be done once a year.
• Grids in the filter will need to be replaced every 2 to 3 years. These range from $150 to $700.

Features You Need To Consider

Now let’s talk about the most important features to consider when it comes to choosing a filter for your swimming pool.

Filter Size

If you can swing it, the size of the filter should always be a little larger than you need. This ensures the filter can handle the power put out by the pool pump. 

The size of your filter must be matched or larger in relation to the size of your pool pump. If too small, its filtration material will break down faster and be less effective.

Filters are rated in GPM (gallons per minute) per square foot, and the filter’s flow rate has to be at least the same GPM as the pump or higher. 

Filter Head Rotation

Sometimes, even with the ideal size filter, things don’t always line up like you expect them to. 

Some (but not all) filters feature a 360° flange clamp in their design, allowing you to rotate the head of the unit. This gives you added flexibility when positioning the filter and attaching the plumbing to it.

Filter Valve

The filter valve is an important component that you should pay attention to. 

Multiport valves are available for both sand and DE filters. They have multi-operational modes to aid in your pool maintenance. 

The most common modes (besides “Filter”) are the “Backwash” and “Rinse” modes. As cartridge filters require you to clean them by hand, they don’t use a multiport valve. 

Multiport valves also have additional settings such as “Waste” (to run dirty water straight out of the pool system), “Recirculate” (to circulate chemicals in the pool, bypassing the filter), “Closed” (prevent water from entering the filter), and “Winter” (for when you winterize your pool).

Cleaning Requirements

Any pool filter will need to be cleaned fairly regularly. 

Sand filters are the easiest to maintain as they only require you to backwash the filter. This is done when the pressure inside the tank gets too high.

A pressure gauge on the unit will need to be monitored so you know when it’s time. Somewhere between the 3 and 5 year mark, the sand will also need to be replaced.

Cartridge filters don’t have backwashing capabilities, and need to be taken apart every 2 to 6 weeks for cleaning. This means removing the filter(s) from the unit and hosing it down to remove debris buildup. Once a year it needs to be deep cleaned using diluted muriatic acid, and after 2 or 3 years the filter(s) will need replacing.

DE filters are the most labor intensive when it comes to cleaning. They do allow for backwashing which is usually done monthly (consult its pressure gauge), but you’ll also have to remove the manifold to hose off the grids and rinse out the tank. 

Additional DE is then re-added to the skimmer and the process starts again. To keep the filters fresh, replace them every 2 to 3 years.

Tank Construction

Filtration tanks are made from either fiberglass or metal. These make some more durable than others.

If your pool equipment is outdoors, it’s always recommended to bring things inside over the winter months, as the extreme cold can crack and damage equipment. 

Installation Difficulty

The nice thing about installing a pool filter is that it will always be located in the same position along your chain of pool equipment. 

The bad thing is some filters can be a bit more involved to set up. Sand filters are a perfect example, as you have to follow procedural steps to set up the filter, and even manually add sand to the tank.

However, installing them isn’t difficult as long as you can follow basic instructions. 

Of note, some filters don’t include all the necessary fittings that you’ll need (ie. pump to filter), so you may have to source these on your own.

Other Things To Consider

Let’s finish on a few final things you should take into consideration.

Do You Have A Saltwater Pool?

Yes, you can use these filters with a saltwater pool.

The saltwater system still requires a filter, and the only differences between sand, cartridge, or DE will be the micron size they can remove, and of course the cost.

Do You Have An Above Ground Pool?

If you have an above ground pool, the same applies.

A large majority of above ground pool owners choose a sand filter for its ease of use and low cost (especially with the size above ground pools being smaller), but filter choice is up to you.

Our Top Pick