Pool Filter Comparison: Which One Should I Buy?
When it comes to choosing a filter for your swimming pool, there are a lot of factors to consider. Things like maintenance requirements, initial expenses, upkeep, cleaning efficiency, pool size and operating costs generally come to mind. In the end, perhaps the most important question to consider in your pool filter comparison is which type will work best for you and your budget. To answer that question, it’s most helpful to understand the differences between the three different styles of pool filters: sand, cartridge and diatomaceous earth. Knowing the variances between these filters will help to better weigh your options.
Sand filters are large tanks filled with pool filter sand, specifically designed to work with the filter system and remove debris as small as 20 microns. There are also a few accepted filter media alternatives – including filter glass and Zeo sand – to increase your filtration power and remove debris within a smaller micron size range. The pump pushes water from the pool through the sand inside the tank, where the water is filtered and cleaned before returning to the pool. The initial purchase cost to purchase is much less than other types of filters, and the maintenance required is relatively low.
Over time, the accumulation of dirt and debris will build up pressure within the tank. When the tank’s pressure gauge reads 8-10 psi higher than where it started, all you have to do is run a backwash and rinse cycle to clear the filter. The filter sand itself holds up rather well and only needs to be replaced every 5-7 years, which saves even more time and money for the user. Alternative filter media tends to be pricier and needs to be replaced at closer intervals.
- Lowest purchase price
- Easy to operate and maintain
- Filter sand lasts 5-7 years
- Alternative filter media available to boost filtration power
- Popular option for both in ground and above ground pools
- Backwashing and rinsing process wastes water
- Some local regulations restrict backwashing
- Micron size filtered by sand (20 microns) is higher than other filters
- High pressure system can decrease energy efficiency and increase wear on pumps
The tanks in cartridge filters are generally smaller than sand filters and offer high filtration performance in an energy efficient package. A cylindrical filter cartridge sits within the tank, which filters water through its pleated paper-like surface of the cartridge before the water returns to the pool. The cartridge design offers several benefits. Pleats increase the surface area available for capturing dirt and debris (as small as 5 microns), which lowers flow resistance and ensures maximum efficiency for your pump. In fact, cartridge filters work best at lower speeds, making them ideal for pairing with a variable speed pool pump.
Similar to the other filters, a pressure gauge reading of 8-10 psi higher than the starting pressure signals that it’s time to clean the cartridge. Although cartridge filters don’t require backwashing, they do still need a thorough cleaning a couple times per season. This can be done by simply removing the cartridge from the tank and spraying it down with a hose, making sure to clean the areas between the pleats. A filter wand or flosser can make this task much easier. You can also soak the cartridge in a special cartridge cleaning solution to help eliminate stubborn dirt or stains. Repeated use will gradually decrease the filtration efficiency of your unit. Cartridges should be replaced every 2-3 years for best results.
- Most energy efficient
- Filters debris as small as 5 microns
- Cartridges are easy to replace
- No backwashing required
- Works well for both in ground and above ground pools
- Cartridges need replaced every 2-3 years
- Cleaning process is more hands-on
- Higher purchase cost
Diatomaceous Earth Filters
Diatomaceous earth filters, also known as DE filters, offer superior levels of filtration – as small as 3 microns. DE is a naturally occurring sedimentary rock made from the fossilized exoskeletons of diatoms, a type of microalgae. This rock crumbles easily and is used with pool filters in its powdered form. DE powder works by clinging to a series of grids/fingers within the unit’s large tank. This forms a thin, cakey layer that captures even the smallest debris from your pool. Although DE filters offer better filtration, they do require more frequent maintenance and are more expensive than sand or cartridge filters.
Just like the other styles of filters, a pressure gauge reading of 8-10 psi above normal lets you know it’s time to clear the filter. Unlike sand filters, DE filters require an additional step after the backwashing process is complete; the DE powder must be replaced every time the filter is cleaned or backwashed. This can be a bit more costly and require more maintenance time depending on cleaning frequency. Most regularly-used pools require backwashing at least once a month. DE powder is added quickly and easily through the skimmer, but the entire unit should be broken down and thoroughly cleaned at least once or twice a year.
- Filters debris as small as 3 microns
- Easy to replace DE powder
- Often used for in ground pools, but above ground models available
- Highest purchase cost
- Higher maintenance levels
- New DE powder needs added after each backwash
- Requires thorough cleaning once or twice per year
- DE in powder form is carcinogenic
- Some local regulations restrict backwashing
It’s important to consider all the pros and cons of each filter type before making your investment. When it comes to the pool pump you’re pairing it with, the general rule of thumb is that the filter’s GPM (gallons per minute) flow rate should be higher than the pump’s GPM to avoid damage to your filtration system. It’s usually best to opt for a larger filter than your pool actually requires. Regardless which type you choose, purchasing a quality filter will help keep your pool sparkling all season.