Choosing the Best Pool Filter (Sand vs. Cartridge vs. D.E.)

Your pool's filter system is the single most important piece of equipment for maintaining clear and clean water. It works tirelessly to remove dirt, debris, and impurities. When choosing a filter, you have three main options: Sand, Cartridge, and Diatomaceous Earth (D.E.). Each has distinct advantages and disadvantages in terms of filtration performance, maintenance requirements, and long-term cost. This guide will provide a detailed comparison to help you make the best choice for your pool and lifestyle.

Filtration Ability: How Clean is Clean?

The primary job of a filter is to trap small particles. The smaller the particle a filter can remove, the clearer your water will be. This is measured in microns.

• Sand Filters: These are the least effective at fine filtration, typically trapping particles in the 20-40 micron range. While they do a good job of keeping the water clear, they won't produce the same "polished" look as the other two types.
• Cartridge Filters: These offer a significant step up, filtering particles down to 10-20 microns. This finer filtration results in visibly clearer water.
• Diatomaceous Earth (D.E.) Filters: D.E. filters provide the best filtration available, capturing particles as small as 1-3 microns. This results in exceptionally sparkling, crystal-clear water that is unmatched by other filter types.

Winner for Filtration: D.E. Filters

Maintenance: How Much Work is Involved?

This is where the three types differ the most, and it's a major factor for most pool owners.

Sand Filters

Maintenance is relatively easy. When the pressure gauge on the filter reads 8-10 PSI above its clean/starting pressure, you perform a "backwash." This involves turning a valve to reverse the water flow through the filter, flushing the trapped dirt out to waste. This process takes just a few minutes. The sand itself only needs to be replaced every 5-7 years.

Cartridge Filters

These require no backwashing, which saves water. When the pressure is high, you turn off the system, remove the cartridge(s), and hose them down thoroughly. This is a more manual process that can take 15-30 minutes. The cartridges should be deep-cleaned with a filter cleaner solution 1-2 times per season. The cartridges themselves need to be replaced every 2-4 years, depending on usage and care.

D.E. Filters

D.E. filter maintenance is the most involved. Like a sand filter, it requires backwashing when the pressure is high. However, after backwashing, you must add new D.E. powder to the system through the skimmer to recoat the filter grids. This D.E. powder is a known carcinogen when inhaled, so a mask should be worn when handling it. The entire filter must be disassembled and the grids deep-cleaned annually, which is a more complex job.

Winner for Ease of Maintenance: Sand Filters

Cost: Upfront and Long-Term

Cost is a major consideration, both for the initial purchase and ongoing expenses.

• Upfront Cost: Sand filters are generally the least expensive to purchase. Cartridge filters are moderately priced, and D.E. filters are the most expensive.
• Long-Term Cost: This is more complex.
  • Sand: The only recurring cost is replacing the sand every 5-7 years, which is relatively inexpensive. However, backwashing wastes water and chemicals, which adds to operating costs.
  • Cartridge: No water is wasted, which saves on water and chemical costs. The main expense is replacing the cartridges every 2-4 years, which can be costly ($100 - $400+ depending on the filter size).
  • D.E.: You have the water and chemical waste from backwashing, plus the ongoing cost of buying D.E. powder. The filter grids also need eventual replacement, which is a significant expense.

Winner for Cost: It's a trade-off. Sand filters have the lowest upfront and parts cost, but higher water/chemical costs. Cartridge filters have a higher parts cost but save on water. D.E. is the most expensive in all categories.

Summary: Which Filter is Right for You?

Ultimately, the "best" filter depends on your priorities. All three types will keep your pool safe and clean if properly maintained. Consider your budget, how much time you want to spend on maintenance, and how important sparkling, polished water is to you before making your final decision. No matter which you choose, remember that consistent water testing and proper chemical balance are just as important as filtration for a healthy pool.