When it comes to keeping your swimming pool clean and clear, you need a quality filter to run the water through. The two main pool filters are the cartridge filter and the sand filters although there is a third one, the diatomaceous earth (D.E) filter, with features almost similar to those of the sand filter. In this guide, we focus on the cartridge and sand filters in terms of how they differ or are similar.
In choosing between pool filters and sand filters for your pool, we’ll focus on some important aspects such as the ease of use, the size of the dirt particles removed, the reliability of the filter among many other factors. Between the two, it’s all up to the user although the cartridge filter slightly edges the sand filter in some vital areas.
Cartridge Pool Filter Vs Sand Filters:
|Cartridge Pool Filter||Sand Filter|
|Size of dirt and debris removed||10-15 microns||20-40 microns|
|Ease of use||Needs frequent cleaning and careful handling.||Easy to use as it doesn’t require frequent cleaning or too much careful handling.|
|Reliability||Highly reliable.||Highly reliable.|
|Pool GPM (gallons per minute)||Works well for low GPM pools.||Works well for higher GPM pools.|
|Level of maintenance required||Low and simple maintenance required.||Requires more and frequent maintenance.|
|Backwashing||No backwashing and will thus not waste salt on salt water pools.||Backwashing involved and will thus leads to higher salt costs on salt water pools.|
|Cost||Higher purchase and running costs.||Lower purchase and running costs.|
NB: 1 micron = 0.000001 meters
As their name suggests, sand filters use sand to clean water and the filtration process is simply running the water through the sand to trap the debris in the sand. The sand used, however, isn’t normal sand but specially designed rough shaped pool filter sand meant specifically for this purpose.
Sand filters are usually quite affordable and thus favored by lots of people. You can use various types of sand including #20 silica sand, zeosand, filterglass or even D.E. powder. These usualy have better filtration than other types of sand for the same process.
The filtration process is the same whether it’s for in-ground or above ground pools. The water enters the filter from the top then runs through the sand where it’s filtered. The amount of dirt captured depends on the sand used with sand filters above to capture substances above 20 microns in size.
The water then exits the pool from the bottom part and back into the pool. With sand filters, there is a backwashing effect that occurs when the water flows out through the waste line cleaning the filter in the process. For this reason, you’ll need to replace the sand every 5 to 8 years as per your usage rate.
Few sand filters have automatic backwashing capabilities. Instead, they build up pressure on the upper side of the filtration chamber and gives a signal for when backwashing is needed. Thankfully, the backwashing process is an easy one.
Sand filter pros
On the upside, you have the following advantages with sand filters:
- Easy to use and simple to operate.
- Best suited to pools with a high GPM capacity.
- Removes as low as 20 microns of debris and dirt.
- Highly reliable.
- Needs sand replacement every 5 to 8 years.
- Sand filter media is quite cheap to acquire.
Sand filter cons
On the downside, you have the following disadvantages with sand filters:
- They’re not great with pools at a lower GPM capacity.
- Needs frequent maintenance.
- The backwashing effect causes higher salt costs on salt water pools.
- Backwashing negatively affects the water pressure balance.
- Lower filtering ability than cartridge filters (20 microns vs 10 microns for the cartridge filter).
With these aspects in mind, you can be sure of what you’re getting with a sand pool filter.
Cartridge filters use filter cartridges instead of sand to filter the water. Owing to this, they can filter as twice as much dirt and debris than sand filters. The cartridges have a higher surface area than sand and thus the water takes longer to go through them hence the better level of filtration. They can filter smaller particles as small as 10 microns for the same reason.
The lack of a backwashing process step makes this filter much easier to maintain. They’re great for low GPM pools and won’t waste salt on a salt water pool thanks to the lack of a backwashing stage. These features make them a bit costlier to acquire and use. They’re also relatively more delicate compared to sand filters.
Cartridge filter pros
The best bits about having a cartridge filter include the following:
- Removes dirt and debris as small as 10 microns.
- Doesn’t waste salt on salt water pools.
- No backwashing step needed.
- Simpler to maintain compared to other filters.
- Utilizes lower pump pressure (GPM) thus saving on energy.
- Low wear and tear on the parts of the pool pump owing to the low pressure required.
Cartridge filter cons
The downside to having this pump is as follows:
- Costs more than other types of filters.
- Need more and frequent cleaning.
- Need more careful handling.
- Cartridges need to be washed at least twice a year.
- Needs cartridge replacement every 1 to 3 years.
You can be sure that your cartridge filter will do a better filtration job than sand filter, but cost significantly more.
Which is the better filter?
The decision between the two types of filters is subjective and dependent on many different factors such as following:
Whether the pool is salty or not
If your pool is salty or will one day be salty, you should go for a cartridge filter. This is because it’ll cost you less to use owing to the lack of a backwash process.
If you can backwash the sand filter
If you have a location to comfortably backwash the sand filter, you can use the sand filter as it’ll cost you less in the long term.
How clean you want the water
Both sand and cartridge filters will give you sparkling clean water. If, however, you need very clean water on a microscopic level, the cartridge filter will do a better job.
How much debris there is in your area
If you live in an area with lots of dust and debris floating around, you’re better off with a sand filter since it’s easy to maintain. A cartridge filter in such an area will cost too much as you’ll have to carry out frequent cleaning exercise for the cartridges. This, in itself, is no easy task to do especially on a frequent basis.
Of note is the fact that you’ll still need to treat your pool with the appropriate chemicals. While the filters discussed here can remove a majority of the debris from the pool water, they can’t remove smaller microorganisms such as disease-causing ones. Even dust at about 4 microns in size cannot be captured by a majority of the pool filters.