Selecting a Pool Filter
Pool filters are an essential part to your swimming pool system. Sanitizers (chorine etc) work to kill bacteria and other containments, but, the filter actually removes them from the water. Without it, your pool water would grow cloudy and fill with debris.
Here at www.poolandspacentre.co.uk we want to highlight some important info to help you choose what right for you. We know whatever filter we supply must trap contaminants, be easy to clean and maintain, and last more than just a few years.
Pool Filter Types
There are a number of filters options: sand, cartridge, and diatomaceous earth. The replacement frequency, and filtration rates differ by type.
What is a Micron and why do we need to know?
Micron is short for micrometer, one millionth of a metre. Pool filters measure the size of contaminants they’re capable of removing in microns.
How small?? A single strand of human hair is about 50 microns (.05 millimeters in diameter). Some bacteria measure about 2 microns, (.002 millimeters in diameter).
Whether the chlorine has eliminated them or not, bacteria and other contaminants can only be filtered out if the filter media (the material that actually does the filtering) is fine enough and compact to collect these tiny particles.
By far the most popular filter and for those on a normal budget who want to minimise maintenance, this is the choice for you. It’s perfect for large pools because it won’t clog up as easily as other filters.
So heres how it works, the pool pump pulls water in from the skimmers, pushes it through your pipework into a large filtration tank full of silica sand (other media is available). It grabs particles that measure 20 microns and larger.
A grain of sand is prickly, lots of its rough edges grab contaminants and debris that pass through the filter. As time passes, water flow smooths down the rough edges through erosion, eventually they aren’t able to capture anything.
Particles trapped within the sand build up over the life of the filter. This helps trap smaller particles, even as the sand itself begins to smooth out. Eventually, this prevents sproper water flow through the filter, reducing the filter’s efficiency.
The filter pressure gauge alerts you to increasing internal pressure — a sign to backwash the filter. This easy cleaning method reversing the filter water flow, flushes all debris to waste. Yeh preston clean again....
Silica sand captures particles of 20 microns or larger, so pool water chemistry is a must. If you don't sanitise your pool enough to kill those 2-micron bacteria, a sand filter won't catch them either, and they’ll be floating around in your pool with you. Nice....
Silica sand is the standard and most popular media by far in sand filters, you can slightly increase filtration efficiency by adding D.E. powder after backwashing or replacing the sand, but this is a bit of an overkill for the normal customer.
You can also entirely replace the silica with one of two alternatives.
ZeoSand: This is made from a mineral called zeolite. It is a crystal-like shape which naturally traps smaller contaminants than silica. This improves water clarity and requires less frequent backwashing. ZeoSand lasts about five years, so its lifespan is similar to silica.
Filter Glass: This is finely crushed, recycled glass. It is negatively electrical charged which attracts positively charged particles, such as iron and manganese, while filtering debris as small as 5 microns . It lasts up to three times longer than pool sand.
Sand Filter Pros:
- Lower overall cost
- Simpler maintenance
- Silica Sand lasts 5-7 years before needing to be changed
- Filtration efficiency can be boosted with additives alternative media
Sand Filter Cons
- 20micron filtration is the least effective of the three types
- Backwashing and rinsing wastes water
- Building pressure decreases filter efficiency
Typically slightly more expensive than sand filters, cartridge filters are just as easy & simple to maintain, and are more effective as long as your pool is not huge.
Inside a tank (slightly smaller thans sand filter) is a pleated polyester filter media cylinder. Water flows into the tank and through the pleats. Debris as small as 10 microns is captured in the filter, then clean water heads back to the pool.
Cartridges are normally inexpensive & energy efficient. As the filter collects contaminants, itw will require thorough cleaning. Rather than backwashing, simply remove the cartridge from the tank, spray it with a hose to remove debris and dirt.
Occasionally, spray it with filter cleaner , and on a regular basis, soak it in chemical filter cleaning solution. This is a bit more extra work for you than backwashing, but it wastes less water.
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
Diatomaceous Earth (D.E.) Filters
Expensive and rare in Europe, a lot of maintenance but happens to filter the smallest particles (5 microns) of all three types of filters:
D.E. filter tanks have grids / fingers covered in a crumbly, white powder, made from the crushed fossilized remains of tiny aquatic organisms called diatoms composed of silica.
Backwash or Bump Cleaning
A pressure gauge on the tank will highlight the time to clean your D.E. filter. Typically, D.E. filters are backwashed just like sand filters. Some brands feature a bump handle, which lets you knock the used D.E. off the fingers to clean them.
You need to add more D.E. powder after every clean. It can be difficult to know exactly how much to add, so it’s important to disassemble and clean the filter by hand at least once a year.
After cleaning the filter, add D.E. powder directly to the pool skimmer as you’ll get much better coverage this way. Mix the D.E with enough water to make a slurry, whilst running the pool pump, then slowly pour the solution directly into the skimmer.
As the D.E. passes through the filter, it will evenly distribute over the grids. Wait a while before swimming as to give the mixture time to fully integrate with the filter, so you may want to do this in the evening, and then run your pump overnight.
Check your local regulations specifying how to legally dispose of used D.E. as when it’s rinsed from the grids, D.E. powder can build up over time, creating a concrete-like residue that can clog drains.
Usually, you’ll be allowed to empty old D.E. into a container and take it to the trip or out with your rubbish place it in the trash. Cancer Risk with D.E. Filters
Important: Safety first. Prevent accidental inhalation by wearing a chemical mask when you handle D.E. powder. Store correctly & immediately clean up any spilled powder.
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
The most common issue we come across is the wrong sized pump for the filter, a pool filter and a pump go hand in hand together. The filter can’t function properly without the correct size pump for your pool.
So to avoid this mistake, before you settle on a pool filter, make sure you have the right size pool pump. Speak to us on this as we have specific calculations to help you get the right pump for your filter and vice versa.
The Best Filter is the One That’s Best For You
We cater for every budget, it’s really up to you what’s best for your lifestyle, essentially you can spend less money for less maintenance and less filtering, or, invest a bit more up front for better filtering for the cost of more time and work. .
No matter what pool filter you choose, remember that keeping your water chemistry balanced gets you more than halfway to a clean pool. Stay on top of cleaning and maintenance, and your filter can last you for many years to come.