Swimming Filter Buying Guide

Which Filter is Right for Me?

The Importance and Function of the Filter

To prepare you to choose the perfect filter, let's start with explaining the job of the filter in your pool. The filter and pump are the heart and lungs of the pool circulation and filtration system. The primary purpose of the filter is to keep your pool clean by removing undissolved debris from the pool water.

How The Filter Works

Pool water comes from the circulation pump into the filter where small debris particles are removed through depth or surface filtration, and then goes on to the heater or back to the pool.

A filter works through mechanical separation of water and debris through surface or depth filtration. Sand filters use special filter sand, cartridge filters pass water through a fibrous element, and DE filters pass water through a thin layer of diatomaceous earth that is coated onto a grid.

A gauge located on the filter or valve can be used to measure the back pressure or resistance in your filter system. When the pressure increases by 10 psi, the filter should be cleaned to reduce resistance and improve water flow.

Cartridge filters require disassembly and cleaning of the cartridge periodically to remove debris from the filter.

DE and Sand filters require periodic backwashing to remove debris from the filter. To accomplish this water is directed through the pool filter by a valve (multiport, vertical, or other). Once the water runs through the filter, it flows to the pool heater or back into the pool. To backwash, the valve is manipulated to reverse flow and direct debris-filled water to waste.

Over all Ranking on Ease of use, Water Clarity, and Maintenance Cost

Sand Filter

Over all Ranking on Ease of use, Water Clarity, and Maintenance Cost

  • Second Place for Ease of Use
    • Fairly simple to use, Backwashing takes a few minutes, but you do lose water when doing so. 
  • Last Place for water Clarity
    • Filters about 30 to 34 microns so some of the smaller particles can pass thru the filter
  • Second Place for Maintenance cost
    • Sand is fairly cheep and doesn't need to be changed that often

In this method, impurities are extracted from the water utilizing sand to collect and attract the debris. Sand filters must be backwashed (running it in reverse) to unload the water waste. This is a manual process that must be performed every two to three weeks. Sand filters trap debris as small as 20 to 40 microns. Depending on the Size of the filter the sand should be changed every two to five years

Sand is the oldest and most popular method of filtration

Cartridge Filters

Over all Ranking on Ease of use, Water Clarity, and Maintenance Cost

  • First Place for Ease of Use
    • Simply spray off the cartridge and re-use
  • Second Place for water Clarity
    • Filters about 10 to 14 Microns. Still may need some clarifiers to give that perfect sparkle.
  • Last Place for Maintenance cost
    • Replacement Cartridges are typically a higher up-front cost, about every year to every other year the cartridge should be replaced.

Cartridge filtration has been available for a relatively long time, but has only recently begun to enjoy rapid growth and acceptance.

Cartridge filters have a greater surface area than sand allowing for fewer clogs and easier maintenance. Cartridge filters are designed to run at lower pressure than sand which puts less backpressure on the pump, providing more flow and turnover. Cartridge filters should be cleaned once or twice a season by simply hosing them off. Cartridge element filters trap debris as small as 10 to 15 microns.

Diatomaceous (DE) Filters

Over all Ranking on Ease of use, Water Clarity, and Maintenance Cost

  • Last Place place for Ease of Use
    • Just a littler bit more maintenance then Sand Filters and Cartridge filters. D.E. filters use grids or collectors that hold the D.E. The D.E. powder is the actual filter so when they are backwashed or cleaned the D.E. needs to be replaced. Easy to do but one more step.
  • First Place for water Clarity
    • 0 to 4 Microns the overall clearest water of all the filter types.
  • First Place for Maintenance cost
    • D.E. is relatively cheap a 25lb Bag (about a seasons worth) is about $30.00

Diatomaceous earth is a porous powder with microscopic openings that when magnified look like tiny sponges. Clear water can pass through these openings, but particles, as small as two to five microns, are trapped during the first pass through the media. D.E. filters have internal elements that become coated with D.E. It is this 'filter cake' that strains dirt, dust and algae from the water.