When to Examine Your Pool Filter

• If your sand filter is not filtering as effectively as it should, you may begin to see buildup of grease, oils, scale and other impurities on the surface of the pool area. Other symptoms include diminished circulation of water from the pumping system into the pool water and the water may even appear scummy or discolored upon close inspection. Even in the absence of these symptoms, the sand in a pool filter should be changed every two to give years at the least.
  
  

Sand Cleaning

• As counterintuitive as it may seem, sand filters work better when they are dirty than when they are clean. Clean sand is meant to trap particles that are 50 microns or larger, but as the sand layer becomes more dense with trapped particles, it can trap particles that are 20 microns or smaller. Some pool experts recommend removing the sand periodically to have it chemically cleaned and then putting the same sand back into the filter, but if you are going to go to the trouble of removing the sand form the filter you may as well replace it with new sand since sand that has combined with trapped particles will need to be replaced soon anyway.
  
  

Sand Replacement

• The methods used for removing the sand from your pool filter vary heavily depending on the design and brand of the sand filter you use, as does the choice of what type of sand to buy. Consult the product's documentation to see what type of sand they recommend for their filters and how to disassemble the filter for the purposes of removing the sand. If you do not still have the product documentation, consult a local pool supply store or pool cleaning company for sand recommendations.
  
  

Preventative Care & Other Measures

• If you use a biguanide mixture as an alternative to chlorine for disinfecting your pool water, you may need to increase the frequency of sand replacement to once per year. Oils resulting from biguanide usage can collect inside a sand filter and "gum it up," diminishing its ability to filter the pool water. Regular backwashing and maintenance of all the filtering and pumping components of your pool will also help keep the need to change pool filter sand to a minimum.