Pool Filters

Swimming pools are the ultimate in entertainment and relaxation, but take a backstage when the water is cloudy or green. Swimming pool filters do the heavy lifting by removing particles down to very small sizes, which improves the efficacy of your sanitizer, and helps to keep pool water balanced, too.


There are 3 types of pool filters, Sand Filters, D.E. Filters and Cartridge pool filters. All 3 filter types are effective when sized correctly, and when water is balanced and well sanitized.

FILTER MEDIA: The media is what’s inside of the filter tank. Sand, Pleated Cartridges, or DE Grids, coated with DE (diatomaceous earth) powder. Sand makes a good filter medium, however there are many good sand alternatives such as FilterGlass, ZeoSand and FilterBalls. For DE filters, the filter media is the DE powder, which coats the DE grids inside the tank. After backwashing to clean the filter, fresh DE powder is added to the skimmer to recoat the grids. Filter Cartridges are another type of filter media, pleated polyester filters that are removed and hosed clean when filter tank pressure rises.

FILTER EFFICIENCY: DE filters are the most efficient, filtering down to the smallest particle size, in the shortest amount of time. However, I would rather have a very large sand filter than a very small DE filter, because filter size is important. The eye can see particles at about 35 microns or higher, so any pool filter type will be adequate to prevent cloudy water. Sand filters can allow very small silt to pass through, but as the sand bed begins to load up with dirt, it traps smaller particles.

POOL FILTER COST: DE filters cost the most to buy in most cases, due to the more complicated nature of their design. Cartridge filters can also cost as much as a DE filter, when sized correctly for inground pools. Sand filters are the least expensive pool filter to buy, but keep in mind that you also have to buy the sand separately.

POOL FILTER MEDIA COST: Eventually, your filter media (sand, grids or cartridges) will need to be replaced, as it wears out over time. DE grids cost about $100 for replacement grids - more or less, depending on filter size. Filter cartridges are replaced more often, and the cost ranges widely from $50 to $350, depending on the size and number of filter cartridges. Filter sand can range widely, from 20 cents per pound for regular filter sand, to several dollars per pound for longer lasting alternatives.

FILTER WATER USAGE: If you are interested in saving water, cartridge pool filters waste the least amount of water, because they are not backwashed but are hosed clean. DE and sand filters can use hundreds of gallons of water during a 3 minute backwash. Over a summer season, this can amount to thousands of gallons lost to backwashing. Another way to save water is to buy a larger pool filter, which will require backwashing less often.

FILTER REPAIRS: DE filters have the most parts, and probably also require filter part repairs more often. Sand filters are fairly simple, but like DE filters, may have a multiport valve, which can account for more than its share of repairs. Cartridge filters have no filter valve, and a simple design, which may result in the fewest repairs of all 3 pool filter types.

FILTER MAINTENANCE: Sand filters are the easiest to operate and to clean or backwash. DE filters are also easy to backwash, but require fresh DE powder added afterwards, and need an annual cleaning of the grids with a strong garden hose. Cartridge filters have a cleaning process that takes more time, as the tank must be disassembled and each cartridge hosed clean manually.

DOES FILTER SIZE MATTER?: Do yourself a favor, and buy as much filter as you can afford, larger than you think you need, and larger than the turnover in gallons listed in the manufacturer spec tables. A larger filter is more efficient and more effective, can save money with reduced chemical and pump run costs, and saves time and energy by requiring less service and maintenance. A larger filter runs longer between cleanings, as it has a greater dirt load capacity, but larger filters also produce better filtration, trapping more dirt in a shorter amount of time. In addition, if water conditions turn bad, or for spring openings, larger filters restore water clarity much faster than undersized pool filters. So yes, filter size does matter – you will never regret spending a few hundred dollars more for a larger pool filter.