Types of Swimming Pool Filters
The first step to choosing the best pool filter is knowing what your options are. You have three types of filters to choose from: sand, cartridge, and diatomaceous earth, or D.E. Price, replacement frequency, and filtration rates differ by type. And if you’re wondering how to clean a pool filter, that will also depend on the type you select.
If you’re on a budget, and you want to spend minimal time on maintenance, a sand filter is the best choice for you. It’s also optimal for large pools because it won’t clog as easily as other filters.
Your pool pump sucks water in from the skimmers, then pushes it through a large filtration tank full of sand. The standard media used inside the tank is #20 silica sand. It grabs particles that measure 20 microns and larger.
Each grain of sand is, for lack of a better word, prickly. If you could look at it under a microscope, you’d see it has lots of little rough edges all around it, which is how it grabs contaminants and debris that come into the filter from the pump.
As weeks and years pass, and more water flows through the filter, those rough edges are slowly worn down by erosion, eventually becoming smooth surfaces that aren’t able to capture anything.
At the same time, the particles trapped within the sand will build up over the life of the filter. This can actually help trap smaller particles, even as the sand itself begins to smooth out. But eventually, it will prevent proper water flow through the filter, reducing the filter’s efficiency.
A pressure gauge on the side or on top of the filter will alert you to increasing internal pressure—a sign it’s time to backwash the filter. This easy cleaning method the filter reverses the water flow, flushing all the debris to a waste line and essentially flushes the sand.
Because the silica captures particles of 20 microns or larger, you’ll really need to stay on top of your pool water chemistry. If there’s not enough sanitizer in your pool to kill those tiny, 2-micron bacteria, a sand filter isn’t going to catch them either, and they’ll be floating around in your pool with you.
Sand Filter Pros:
- Lower cost
- Easier maintenance
- Sand lasts five to seven years before needing to be changed
- Filtration efficiency can be boosted with additives alternative media
Sand Filter Cons:
- 20-micron filtration is the least effective of the three types
- Backwashing and rinsing wastes water
- Building pressure decreases filter efficiency
Cartridge Filter Pros:
- Filters contaminants as small as 10 microns
- No backwashing; less water waste
- Performs well at low speeds, such as with variable-speed pumps
Cartridge Filter Cons:
- More work than sand filters
- Lasts only 2 to 3 years
- Deep cleaning required 1 to 2 times per year
Backwash or Bump Cleaning
How to Add New D.E. to the Filter
- Mix the D.E with enough water to make a slurry, which will look like a thin, creamy solution.
- Make sure the pool pump is running.
- Slowly pour the solution directly into the skimmer.
D.E. Filter Pros:
- Filters contaminants as small as 5 microns
- D.E. powder can be added through the pool skimmer
- No caustic chemicals are required for cleaning
D.E. Filter Cons:
- Highest cost filter
- Annual cleaning is a lot of work
- Grids need replacement every 2 to 3 years
- Hard to find for above ground pools
- Backwashing may be restricted by locale
- D.E. powder can be harmful if inhaled