Which Pool Filters Are Best?

No two pools are the same.  Even if they are the same size and right next door to each other.  There are, however, characteristics that all swimming pools share.  They all require proper chemical balance.  They all require proper circulation.  In order for the chemicals to work and for the water to circulate, two pieces of equipment are necessary for every pool.  Those two pieces are a swimming pool pump and a swimming pool filter.

Why is Circulation So Important?

The easiest way to visualize the importance of proper circulation is two imagine two very different bodies of water.  First visualize a pond.  You are probably envisioning green, murky water.  That is because ponds are stagnant–they get zero circulation.  Next, imagine a river or stream.  The water is clear and crisp.  This is due to the constant movement of the water.  Moving water is happy water.  It may sound cheesy, but it is the truth.

As our swimming pool pump pushes the water through our various pieces of equipment, it mixes the chemicals and activates them.  Did you know that sanitizer only works when the water is moving?  The swimming pool pump pushes the water through our filter.  Here is where dirt and debris get caught, removing it from our swimming pools.  It is important to circulate our swimming pool water the proper amount of time each day to accomplish what is known as a turnover.   A turnover is when the quantity of water our pool holds (gallons) is passed through the filter.  Once every 24 hours is pretty common, although if you live in a very warm climate, you may opt for two during Summer months.

If you are reluctant to circulate your pool pump the proper amount of time due to high energy costs, or if you are running your pump at night to “save money”...you probably have a single speed pool pump.  Think you can’t afford a quality variable speed pool pump?  Think again!  Check out this one here. 

There are three types of pool filters available.  Let’s talk about which one may be right for you.

Cartridge Filters

Cartridge filters contain a housing that holds 1-4 filter cartridges.  These cartridges have specifically designed pleats that allow the water to flow through at a certain rate.  They are the easiest to clean, so a lot of people go this route.  They may also be a bit less expensive than other filters.  There is less plumbing involved because cartridge filters do not have what is known as a backwash valve. Without this valve, however, you are making some sacrifices.  You have no way to reduce filter pressure other than to completely take the filter apart, remove the cartridges, clean the cartridges and then place them back inside.  Since is a less arduous task, many people opt for a cartridge filter.

The down side.  Cartridge filters offer mediocre filtration quality.  They filter down to only 10-20 microns.  To put things into perspective, a human hair is approximately up to 50 microns, depending on the thickness.  This means there may be noticeable particles in your swimming pool.  Most cartridge owners find themselves needing to use a clarifier, which clumps said particles together, making them easier to be trapped in the filter.  

Sand Filters

A sand filter is a canister filled with a special type of sand known as pool filter sand.  #20 silica to be exact.  As your swimming pool water passes through the sand, dirt and debris is caught by the coarseness of the grains.  They are typically plumbed with what is known as a multiport valve. This allows you to flow the water in the opposite direction through the filter to alleviate some of the pressure the dirt and debris adds.  Filter pressure is measured by a gauge on top of the filter.  This is true for all filters.  The good thing about sand filters is the sand only needs to be changed out every 2-3 years.  This, of course, depends on the quantity of debris and usage.  

The downside.  Sometimes channeling can occur in a sand filter.  This means the swimming pool water has created a channel in the sand and the water just passes through these channels without getting filtered.  Also, if you let your sand filter get too dirty, you can break what are on the bottom of the filter called laterals. A sand filter requires more replacement parts than other filters.  They also only filter down to 20-30 microns.  This means even less water clarity.

Check read this article to learn how to fix your sand pool filter.

Diatomaceous Earth Filters

These filters have the best water filtration.  They filter down to 2-3 microns!  They consist of either 8 grids (for traditional DE filters) or 4 cartridges (for quad DE filters).  These pieces, in and of themselves, do nothing to filter your water.  Their sole purpose is to hold the crushed up diatoms of your diatomaceous earth.  The DE is what filters the water.  Diatomaceous earth filters require a backwash or multiport valve.  This, like a sand filter, allows you to send the water in the opposite direction, knocking off dirt and debris.  Don’t forget to add more DE after you backwash!  You must have somewhere for the water to drain such as a designated p-trap.  DE filters tend to be more expensive due to the quality of the water filtration.  You also have to buy and plumb in the valve.

These are the trickiest filters to fully clean because you need to remove the manifold, which holds the grids in place, all of the grids, hose them off and reassemble.  It can be a pain in the neck to get the grids lined up properly.

Regardless of what filter you decide to go with, when the pressure gauge reads 8-10 PSI above your clean starting pressure, the filter needs to be cleaned or at least backwashed, if you have this option.  Now you know a thing or two about how pool filters work.  See you poolside!

This article describes how to effectively backwash your pool filter. Want to know how to clean the bottom of your pool? Click here to read more.